Was there something that seemed to bring this on?  I agree, its hurtful.  To be honest, one or more of my adult SKs probably feels the same, deep down.  All you can do is disengage.  Be polite and civil.  What does your DH say?

I'm in your shoes. Regardless of the reasons for his behavior, it is not easy being "shunned" from DHs grandkids. The grandkid issue is what pushed me over the cliff. DH's son chose to announce the first grandchild at DH's retirement party, where the majority of the guests were my friends and family brought to the marriage. All about DH being a grandpa while I sat there like the proverbial pink elephant in the room. DH's kids and boss/wife were there. Boss' wife almost fell out of her chair; sat their staring at me, jaw dropped with a shocked look. So much, it caught the attention of DH's oldest daughter, who then looks at me and says, "Its for you too!" While the son looked me square in the face and said nothing. That was it. 12 years of crap treatment by all of DHs kids and a crazy BM....stick a fork in me, I'm done.

I have completely disengaged from DHs kids. It's been 4 years. DH manages his relationships with them. I have my life with DH. We do not share holidays with them. DH visits other times. His pictures with his kids and grands are his. I have printed a few to frame/display in his man cave but that's the extent of my involvement. 

EDIT: I wanted to add....look for other places to share your love. While you can't give it to your husband's grandchildren, there are lots of other places that could use you. I'm surrogate grandmother to my niece's child, Aunt to two new babies in the neighborhood, I volunteer in dog rescue, make quilts for charity....you get the point. Don't let that wonderful love of yours go to waste. Someone really wants and needs you.

You may have raised him but he is not your son, has no (parental) love for you and has made it clear that he hates you. I'd say that you should pretty much shut the door permanently.  As JRI said, if you MUST see him then say the absolutely bare minimum and be polite, nothing more.

As you've already discovered, SS has no intention of including you in his children's lives. That's his right as a parent. Doesn't make it right but it is his call. Fine. Then you should consider these children nothing more than strangers to you, even though your DH is their grandfather. 

Speaking of who, it's time to sit down with your DH and have a serious talk about the way forward. I'd tell him that you will no longer be attending holiday gatherings with SS and his kids since you are purposely ignored and it's been made clear that you will NOT be able to have any relationship with any of them. Secondly, discuss finances. You should not have to support any significant gift giving nor financial assistance to SS and his kids. If DH wants to lavish gifts/money on them, and can't do it without your income supporting it, then it's a no-go.  You should not spend one penny of any money you earn on any person who has told you they hate you. Period. 

Last but not least, you need to disengage.  Stop asking DH about SS and his kids.  If DH starts talking about him change the subject or leave the room (go to the bathroom).  Begin to mentally change your thinking about SS - he is not the child you once knew, he is an adult who wants nothing to do with you. He is a stranger to you, so treat him that way. 

Finally, keep in mind that what goes around comes around. SS has two kids from two different women. I'd say that it won't be long before those young women move on to other men, and kick SS to the curb - including contact with his kids. Then he will know what it is like to be on the outside looking in.   

I know that had to hurt to hear that from someone who you raised and I assume loved.  I'm estranged from my adult SS.  I helped raise him, he came to live with us after BM decided she didn't want him living with her and she couldn't control him.  There are times that I wonder if maybe he's resented me for years because I was the one woman he couldn't run over.  He ran over BM, MIL, and SIL.  He'd cuss at them, smart off, yell, whatever.  He never tried that with me.  He knew better.  I thought we had a good relationship.  He even said he thought of me as his mother and wanted me to be a grandma to his child.  Yet he didn't treat me like a mother.  He bombarded my husband with texts, pictures and videos of the baby.  I never got even one.  Only got a text for Mothers Day while he drove right past me to pick up my MIL.  Think of me as mother?  Really?  Oooookay.  If you say so.  Then he took us out for Fathers Day.  He would've excluded me from that except he knew my husband wouldn't have come.  Had to make himself look good by including me and our bios.  He probably would have excluded my bios too, his half-siblings, but again, he's all about appearances.  That's probably why he never came out and told me he hated me.  His shunning me and ignoring me couldn't be made too obvious.  My husband didn't see it at first.  He did put things together though and confronted him.  All SS did was try to justify his behavior and try to lie his way out of it.  I gave him the space he seemed to want.  It wasn't a problem until we told him we had other plans for Thanksgiving.  Then he had a problem with me and my bios not coming to his baby's dedication.  He never asked about us the day of though.  I guess it made him look bad that we didn't come.  Or likely some people asked where we were, people like his MIL, who seemed like a nice lady.  

Had my husband continued contact with him and his wife, I would've had to deal with it of course but there would've been boundaries.  Your SS already doesn't come to your home.  That's good.  He shouldn't be allowed there under any circumstances.  I would refuse to be anywhere SS was going to be.  I would also refuse to allow my bios around him.  No respectful  relationship with both parents equals no relationship with the kids.  Sorry, SS.  Play stupid games, win stupid prizes. If he wants to keep seeing his son, fine, but outside your home, and not where it interferes with your marriage.  None of your money goes to him or his kids, and while your husband is free to spend his money on them, not to the detriment of your household  finances.  

I d have to say though, at least he was honest.  While it was hurtful,  I'd have more respect for him than I do my own SS.  I can't stand two faced people  who lie, and my SS and his wife are both two faced liars.  She brought out the liar in him, the liar created by BM.  She even managed to turn him against BM.  

I am so sorry!  Out of curiosity, is BM in the picture?  What is BM like if she is around? Is his girlfriend a decent person or is she fake?  In my case, BM had nothing to do with SS turning on me.  He turned on her and she passed away before our falling out.  It was SDIL and he allowed it so really it's his fault.  

With either says he's got issues too and you dodged a bullet here.

i disengaged in late 2018 from all my skids after 4 yrs of marriage and about 4 months into meeting feral disrespectful miniwives sd's. I saw the downward trajectory of their behaviour when hubby shrugged it off

anytime hubby thinks after a year of no contact that i'd want to be at a family event with them present is met with a resounding nooooooo!!!

when hubby tries to guilt me with they apologised and why can't you give them another chance and lets be this 1 happy family, i remind hubby they did not apologise and simply the eldest sd claimed she was sorry if she did anything wrong to hubby, secondly they have been no contact with me or our kids together, thirdly- nobody wants to waste time building a relationship thats one sided, fourthly- they have had multiple times to behave and chosen not to and crossed the line every single time whilst my husband sat there in silence. Fifth- i remind hubby that this is his bloody fault for stupidly marrying a woman he already had warning signs up pre marriage and after the marriage but his desperate need for sex led to him having 3 failed kids with batshit crazy narc egg donor.

then hubby refused to address any issues and swept it under the rug. Then gets to know me and not address with these issues with his kids from exwife and has 2 kids with me. Whenever my hubby would say he shouldn't have married me or have 2 kids with me as it was selfish of him to when he didn't have the balls to address skid issues, i remind him he

shouldn't have married the exwife and have 3 kids with a woman incapable of raising them and did everything to sabotage a pregnancy and that he was simply using us as scapegoats. Also told him the fact his daughters who abandoned him for 5.5 yrs actually guilted him for marrying me and having 2 kids with me and hubby not waiting as a single man pining for them when bio mum was allowed to marry her affair married man guy just goes to show what a total shitshow of dysfunction his kids and ex are and they need to stay the hell away from me and our kids.

my kids are 4.5 & 5 and do not recognise skids as siblings or family. Thats on my husband!!

I have never lived it myself but a very good friend of mine has.  Her DH had a son with his first wife.  They divorced.  He and my friend met a few years later, married and have a daughter.  Both kids are adults.  
 

Her SS told her at a special event, I think that it was a graduation,  that she means nothing to him, though she and his dad put him through college and supported him for years.   
 

She once asked me what she should do with his pronouncement.  I told her to tell his dad that no more marital resources will go to the SS and he will not have access to any assets she participates in procuring.  
 

When SS was in his mid 20s she and her DH bought a beach house.  Guess who has never been to the beach house?  His wife and kids are invited but it has been clear to the SS that if she means nothing to him, he means nothing to she and his father.

The products of these polluted gene pool couplings need to know that they play nice or they don't get to play at all.  This toxic shit should have life long consequences.

Give adult SS what he wants. 

Something's ARE... that simple. 

Why do people try to stick a circle peg into a square hole and MAKE it fit.

Nothing to navigate.

Live your life  joyfully and abundantly. Believe it or not it is OK to be happy.

Your SS is being an aSS. And you will grieve the relationship that you THOUGHT you had with him. And move forward with your bios and the other SS, who does love you.

You mentioned the dynamic of the Bio mother and your two SS. Its called Narcissistic Triangulation. The Golden Child (who doesnt even need to do anything to be "lifted up") and the Scapegoat. Both battling each other for the parents love and approval. Narc supply is what its called. And battles are encouraged.

Its a very toxic dynamic. Im dealing with grieving over SD15 whom I though we had a decent relationship, last April she activated her mother Toxic Troll against me. Long story. I stuck my neck out for her and got my head chopped off. So this Christmas and this years bday will be the last I stick my neck out. Shes on her own. On her own for rides anywhere, on her own for college (I have no bios so I was going to try to help her out) on her own for driving (I was going to give her my car when I get a new one) on her own and she can get her father and mother to do everything...

Shes the Golden Child and her sister SD22 Feral Forger is the self-designated scapegoat. She even likes to tell her parents "you are just the egg donor/sperm donor you dont love me you love SD15!"

So - you have an assortment of great advice. Get yourself through the grief process and move forward with your bios and nice ss. Block block block toxic SS.

The worst betrayal for me was that my ex DH continued to swoon over exSD and BM (thats a whole nother story). Yes I got that SD was his DD . Except a wife expects their DH to always stand beside them. If someone hurts you the one you love would stand beside you, not leave you to be with people who are so cold and calculating towards you. Thats the flucked up part of step life. If this is the case the marriage will always have unsaid, untouched parts that takes away from the couple.

It aint for the faint of heart.

Blessings lady