Hon, your husband may be 'sweet' but he's failing as a partner by allowing his mother to abuse you for years! Her disgusting behaviour should have been shut down at the get-go, rather than continuing for such a length of time.

Until the nasty old crone decides to show a little respect, she should be banned from your home. She is no friend to your marriage and you are very wise to keep your child away from her.

I would keep NastyMIL's nose scrubbed in the stench she perpetrates and let her, and her son, your DH, know that your son will not be allowed anyhwhere near her except under your direct supervistion.

If DH thinks the tripartate sit down with NMIL went well, he is not adequeately in tune with reality to be trusted to keep his nasty mother under control enough to allow her near your child.

Do not tolerate her. Period. Dot.  

tbh... i would have clearly pointed out to her.. you want to see your grandchild.. yet every time we give you a chance.. we are charged for babysitting.. honestly the price of your interest in our child is just a bit steep for us to pay all the time.

Look.. I get it.. I am married to a guy that has two adult daughters (I was SM since they were 5 and 9).. and one of them has two kids.  I have not once WANTED to babysit. or even really spend time with the kids.. not everyone loves kids.. and I guess even if they do.. they don't have to accept being free daycare for their grandkids.. they may have lives too.. but.. she seems to be particularly contrary and difficult.

unfortunately some men (and women) use "sweet and great" as their way to avoid putting their spouses in the position they should be in. He can be as sweet as cotton candy but if he's letting his mom treat you badly, it will always leave a bitter taste in your mouth. 

I think you should ensure your husband sees things from your point of view. You want to be sure that, further down the line, he has your back should you need him and you want him to defend you because he understands why you are upset, not simply because you're his wife.

I can relate. My MIL doesn't like me and I don't like her.  She loooves BM, however.  MIL is more passive aggressive than overt, but her dislike for me (and love fest with BM) is pretty apparent. I don't understand the BM love because BM cheated on her son (many times) and then divorced him.  Go figure.  I have two advantages you don't.  First, she doesn't play favorites between the SDs and DD, and second, she lives 10 hours away.  That one is huge.  My H isn't good at protecting me from her; in fact he'll throw me under the bus.  But distance helps a lot.

Only one woman in control. The one he sleeps with.  You come first now  MIL must now find her place in your life or not. If she wants to see the GK  She now has to do some begging. And realize her place in your life,

I'm glad you pushed back on her. I've had two MILs in my life. The first had been a very controlling parent to my ex and his brothers, and thought she would continue that way. My SIL dealt with her by appeasing her when she was around but avoiding her as much as possible. I was young, stubborn and independent, and I worked hard to create boundaries with her. In the end, we coexisted very nicely and was a big part of our family life. When my current MIL came along, I was older and (I thought) more mature. And she was very easy to get along with, until she wasn't. She and the rest lf the crazy clan love-bombed me for years and I sucked it up, and I laughed off the occasional indiscretion because, like I said, I had matured. I went along with the crazy clan's narrative of who MIL is, which was that she is a sweet person who wouldn't hurt a fly but sometimes says dumb things. Spoiler alert: she's emotionally immature and passive aggressive. She played a huge role in DH's current estrangement from his family, and I don't think I'll ever speak to her again. I didn't mature, I got soft, and I let her walk over me. It hurt her as much as it hurt me because she no longer has a relationship with her son. Boundaries are important. Stand firm on yours.

Both of my MILs were or are decent to me.  Though XMIL did end up being a federal convict for embezzlement.  Though she got caught 12yrs after her daugther and I divorced.

When I read about her conviction in the paper, a number of things that did not pass the smell test while I was married to my XW clarified.

My MIL is great. Friendly, engaging, etc... Interestinly, she got a whole lot easier to deal with after my FIL passed.  She used to be very reactive to positives in my DW's life.  DW and I married when she was 18.  We bought our first house when she was 20.  My MIL had major issues with that.  Jelousy was a big issue with my MIL towards my DD for a very long time.  

I do not think that my MIL  has ever really grasped what her DD has accomplished.  A dual major BS with honors, an MBA with honors, a successful career as a CPA.  MIL has said just that. She is proud of DD but does not really understand what she has accomplished, what she does, etc....  I still believe that my MIL is of the mind that our comfortable life is due more to my career than to my DW's.  While I do well, so does her daughter.  Together, we do very well.

We have worked with my MIL to get her engaged with a wealth manager, stabilized her finances so she is not on the verge of losing her home or her car month to month, and to a point where she can see at least a  non stressful retirement.

For decades she was angry that the dreams she and FIL had never materialized.  

She will be 70 in a couple of months.  She is in a Govt position so her employement is and has been stable for about 10 years. That was another battle that took my DW and I a long time to drive to fruition.  MIL worked a horribly low paying position and fought with us constantly about not being able to do anything else.  We kept guiding her to apply for an Admin role with the State.  She finally did.

Anyway, ILs can be an issue of a different sort. Even when they are decent people. 

When they are not....