Z.A.
That's a hard one.
I personally have cut off all ties between my MIL and myself and my son...but I would NEVER dare to hint much less insist that my husband do the same.
He stays in contact with her as much as he decides to. In the beginning I had to work really hard to smile and be supportive...but now it's second nature. She's his mum, after all. I look at it as: how would I like it if my son's wife made it so I either couldn't see him, or made him feel guilty for seeing me? NOT okay.
Now, I DO have to say, I cut off all contact slowly...first she wasn't allowed to see my son without supervision...and then she wasn't allowed to see either of us at all (unless she was at some big family get together).
ALSO...the issues that caused me to sever ties...are all central to heroine addiction. Before we knew there was a problem, she lost the ability to see my son alone because she LEFT HIM ALONE AT THE PARK while she went to the store. He was 2. Later we found her literally shooting up in my house. Nope. Nada. Zilch. Cut. Off.
It's been my standpoint that if she can string at least a couple years together, then I'll think about it. I've watched her break my DH's heart so many times over the years, that I am further disinclined to acquiesce...but I'll THINK about it.
My husband isn't happy, but he's not happy about the whole situation. He understands my position, and the fact that I'm not willing to use our son as "bait" for her to get well...but that doesn't mean that understanding was gained easily. Unless your husband feels the same way you do, even in clear cut circumstances like mine, we've had to go rounds.
Good Luck