I [28 F] ruined my husband [37 M]'s relationship with his mother and family.

My husband's mother [50s F] is an alcoholic, very severe. I've never liked her, but I tried to remain neutral and be encouraging when he wanted to spend time with her. Then about a year ago we planned to meet up for lunch and an afternoon excursion.
It was a bit of an ordeal from the start; initially she was angling to come stay with us, my husband was adamant she not even cross the threshold because then she could extend her stay (she's done it before), so we agreed to meet about an hour away. We had to rent a car for the day since we don't have one, but he didn't want to drive with her.
The day arrives, we were both absolutely dreading it but I tried to hide it. She showed up late, drunk, and with her boyfriend/fiance [50s M], which was not the plan, and he was ALSO drunk. We pressed on.
Right from the start her date made me incredibly uncomfortable (odd comments, mild racism and sexism, no filter), and I hid it terribly. He picked up on that and responded by becoming more and more aggressive towards me, and made it clear he thought I was being a snob.
Meanwhile my husband's mother is acting almost manic. She's making odd comments, she can't sit still, she keeps repeating the same things over and over, many of which were inappropriate comments I didn't want to hear to begin with. Also she couldn't remember anything about me (my job, my parents names, I think at one point she even forgot my name). We tried to get her to dial back but to no avail.
Towards the end of the meal (longest hour of my life) she asked my husband to go out for a cigarette with her, a chance for them to be alone. I asked him not to leave me alone with this guy, I was genuinely afraid of at this point. This ended up forcing a confrontation; they both got super angry and aggressive, and her date said I was being rude by denying a mother time with her son, and after all the hype he couldn't believe what a loser my husband was.
That's when we left. My husband went to pay at the bar and asked me to go wait in the car when his mom got up to follow us. He said he wouldn't speak to her until she got sober. His last words to her were "I love you mom," and hers were "I doubt it."
Now they haven't spoken in a year, and he's been remembering things from his childhood that he blocked out (forging signatures on A/A forms, having to carry her home because she had passed out, it's been years since she even remembered his birthday). She'll call once in a while, trying to mend fences, but he doesn't answer.
I've been encouraging him to start talking to someone about what happened, but he doesn't think it's necessary. I feel responsible for my husband cutting his mother out of his life, he doesn't speak to anyone else in his family now, either. He insists it's fine, that I'm enough family for him, but this whole mess is a minefield and I want to be supportive and I don't know how.
I know it's not rational; what happened was awful and it was not my fault. Long before I was in his life she was a terrible person. But this has brought up all sorts of things that he has been suppressing for years, I'm worried that some day something will come back to him, or that if she does sober up and falls off the wagon again he will get his heart broken. This is all very unfamiliar territory for me.

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tl;dr: My husband stopped speaking to my alcoholic MIL because of me, I want to support him but don't know how.


Source.

It sounds like it was a pretty toxic relationship between them. Maybe now she will start to take control of her situation.