This sounds really hard. When someones child uses them for ATM or whatever they need, but has no desire for a relationship, its like a death. And you go through grieving period.

Its obvious from what you posted that you need to grieve the loss of the relationship you wished and hoped to have. I would leave the SIL alone and if he doesnt want you there, well thats one less thing you have to purchase for ungrateful person.

That must have been so hard. I wonder why the SD did that to her father?

You sound like a kind-hearted person with a lot of love to give.  But, to protect your heart, I would disengage and expect nothing.  Who knows how tbey will treat you and your DH.

I would ask no questions about graduation, wedding or baby.  You'll know soon enough.  Don't buy baby equipment.  When the baby is tiny, you dont really need anything other than what they'll normally bring (bottles, diapers).   If you see they're bringing baby over more, you can buy the other items.  Unless finances are no problem, I'd go to a children's resale shop in an upscale area and get equipment there.  From my experience, the grandBM gets the grandbaby more than the grandad.  And, some people use access to the baby to punish the stepparents.

As the child gets older, people have less access to free babysitting so you might see the child more then.  Good luck.

Please temper your expectations. Unless no one else can babysit, do not expect to see this child often. If SSIL did not want you at the wedding, do not expect to be invited to his graduation. Don't ask. If you want to know the date, to keep it open in case you are invited, look on the college website. It should be listed on the academic calendar.

Don't buy anything for your home. With a tiny infant, you won't need more than what the parents bring. As the child ages, if you see him/her often, you can pick up a few second hand items. Yard sales are great sources. Thrift stores have lots of gently used toddler toys.

Based on what you have written about the past, the odds of you babysitting frequently are not good. Expect less, and be pleasantly surprised if it occurs. 

Not emotionally, not financially, nor intellectually.

It is a waste.

Period. Dot.

Do not give them any space in your head. The more you prepare and chase them, the more power to manipulate and disappoint you that gives them.

Write them off. Do not get excited. If they engage, great, But that has to be entirely on them.

As for baby gear. If they do end up 'letting' you watch the GSkid, runt o GoowWIll and buy what you need. Or.... just go buy a portable play pen (aka, crib, palette, etc...) and a high chair that clips to the table.  Nothing more.  Why go all in for an entire baby bedroom suite, high chair, etc.....?  This minimizes your financial loss, your emotional baggage when they disappointe you, and prevents you from overly exposing yourself to the risk of them ..... being them.

Past behavior is the best indicator of future behavior. You know what they will do. So ... take care of  yourself.

Lower your excitement and expectations so you won't be disappointed.

IMHO of course,

Had I been your DH at the SD's wedding, would have stood up when she and StepDad were walking down the isle and taken her other arm.  I would nave not said a word. I would have just done it, then I would have kissed my daughter and returned to my seat.  IWNGAF about what anyone thought or said about it.

You cannot tolerate this kind of toxic crap from asshole people.  I get your pain. But... stop tortunring yourself and putting yourself at their emotional victim beck and call.

They have made their preference clear.. I think you need to dial your expectations WAY back.  I would not buy one piece of baby gear.. I know it is hurtful.. but it seems like she feels her dad let her down with the whole car thing.. and probably feels he should have done more.. and resents him now.. BM surely planted plenty of those seeds.

So.. it is what it is.. if she wants to be in your lives.. it will happen.. but you cannot MAKE it happen.  Ultimately.. the baby is not your grandkid anyway.. it's your DH's.. and if he wants to push it.. he can try.. but all you can really do is quietly support him.

I would just dial things back. Let them come to you.

As for buying things, if you do, keep it simple. Maybe a bouncy seat from a consignment shop for now and the baby can sleep in that if they do allow you to babysit. If you find they ask a 2nd time, you can get something else. Shop consignment and save the money. 

I have young nephews (7 weeks and 16 months) I keep highchair booster seat, a jumperoo and bouncy seat. I was given the jumperoo. I bought the others from a used shop and think I have $30 in it. The babies tend to sleep snuggled with me or in the bouncy. You really don't need a lot for them for a while. The older one's parents bring a bag of toys when he comes to play. 

My point is, don't go crazy until you see how this is going to play out. 

Your name (constantlyheartbroken) is an indicator that you are expecting too much from your SD and her husband, and their soon-to-be-born baby.

You are indeed a tender hearted soul and think that if YOU love someone they will (eventually) love you, too.  They won't. The world simply doesn't work that way and especially the stepkid world.  

It sounds like you are overwhelming/smothering your SD and to be honest, most young people in her age demographic don't want their own parents texting them often, let alone a stepmother.  So stop texting her - she probably doesn't like it. Likewise, the SSIL has made it clear he doesn't want you to attend his graduation so stop pushing it.  Don't ask him any questions or confront him. Those kinds of questions are undoubtedly uncomfortable for everyone so stop doing it.  

Understand that this couple does not care to have a close relationship with either you or your DH.  It is awful, it is indeed heartbreaking but it is true. You cannot control them and you cannot control who they have affection for.  It is obvious SD is closer to her own mother and stepfather and you and DH are outliers.  So be it. The only thing that can change is what your expectations of them are - which should be nothing, or minimal at best.  

SD is not your daughter and that baby will not be your grandchild, no matter how much you may "love" her and want to be a grandmother.  You are creating your own heartbreak by expecting it to be that way. This is especially true when it is a stepdaughter having a baby - her own mother is going to be the primary grandmother. It is even more true in your case since you do not have a good relationship with SD.  Likewise, I would expect that BM's husband will be in the primary role as grandfather since SD seems to be much closer to him so your DH should expect to take a back-burner.

I say all this because we are in a similar situation. SD is very close to her mother and her husband, and rarely keep in contact with my SO.  I keep out of it and do the bare minimum.

I don't mean to be abrupt but I see you are in a position to be very, very hurt and I don't want that to happen to you.  You need to start thinking of your SD like she is someone you once used to work with - a person you can be friendly and cordial with once in awhile whenever you may see her, but not someone you have a close relationship with.  When the baby is born send a small token gift (like you would to a former coworker) and then learn to disengage.  There is a section here on STalk which focuses on how to disengage from Step situations that will not get any better. 

Sadly, you are in that position - this is not a situation that will get any better.