loving turned toxic

I need some advice. I have been with my boyfriend (29) for many years (I am a 29yo female). We met when we were children and had dated on and off through our adolescence and officially got back together about 5 years ago as adults (but always remained friends since we were 10 years old) I have always had a stellar relationship with his mother since I was a child. We both thought highly of each other and were very good friends. She is… quirky. Definitely can have manic episodes. Very high highs and extremely low lows. She also has a drinking problem. Gets inappropriately drunk and can be vicious and/or very emotional as a result. I have supported her son through his own battles with addiction and substance abuse. I have loved him deeply since we were children. Even when we weren’t together, I still tried to support him as best as I could. He has now been sober for 5 years. Anyway, over the years, I have brought it to his attention that although I truly love his mother, and family, that they can sometimes be rude and say/do things that I don’t appreciate. I think he is so used to their dynamic that he thought it wouldn’t affect me as much as it was. It would be little things.. small remarks his dad might make, his autistic brother saying something unkind, or his mom saying something mean while drunk. Usually, I could ignore these things and brush it off and move on. Last fall, his mother started asking me what kind of engagement rings I liked. My boyfriend had an idea of this already, and she started interjecting herself. So this clued me into an engagement that may happen within the year. Then she started planning a wedding and reaching out to venues and vendors (we weren’t engaged and still weren’t) While I appreciated her excitement, this rubbed me the wrong way. It spoiled which should have been a surprise. Just one example of her “high highs” (planning a wedding without any input from me). For as long as I have known her, she will get drunk and speak horribly about his father who has cancer. Lusts after old flames. Speaks of their sex life, marriage, financial struggles… all things I DO NOT want to know. Talks about how attractive her son is, inquires and comments about our own sex life. Now that I’m on the outside of it all… I can really start to process it all better and how icky it made me feel. She also had a tendency to get very close to people, find a reason why she thinks they are using her, then cuts them off completely. It’s been her pattern since I met her as a child. She has also been no/low contact with her own toxic mother since I met them. Her mother is worth quite a bit of money, tens of millions is what I have heard. They recently rekindled their relationship, she is at the end of her life and is starting to have memory issues. All of the sudden, his mother is getting designer bags purchased as gifts, and grandmother is paying for a family vacation to Mexico, and other suspicious stuff. About 6 months ago, his mother was going to visit her own mother out of state and offered to “bring back some family jewels” for me. I told her this is unnecessary and that I would rather have her use the time to see if she is in the will. I told her family gets weird when it comes to money and inheritances and I want her to be prepared for however it’s going to go. I also mentioned how great it would be if she was in the will, so that she and her husband could purchase a home (they are in their 60s and still rent) and to set up each of their children for success (my boyfriend, his autistic brother that will never be independent, and his younger sister that has a lot of growing up to do and is in her mid 20s) in the moment, she didn’t want to talk about it and shut down the convo. I didn’t think much of it. She and I had a no-boundaries type relationship, as demonstrated above. I go back to her house a few nights later and she gets drunk and tells me that she thinks that I have ulterior motives for dating her son and that I’m out for money. My boyfriends and I were hurt and shocked. This was in January and it has only escalated and gotten worse since. Sober, she has stood her ground and says she meant what she said, despite her comments completely shattering my heart. She called me months later, drunk, and proceeded to call me a narcissistic, manipulative bitch that’s out out for money. When confronted by my boyfriend, while she was sober, she stated that she still stands by her comments. He told her she has drawn a line and that he is on my team, that things will change between them, and she owes me an apology. She doesn’t care. It’s been 6 months. I have texted her on her birthday and sent Mother’s Day flowers. No response. This has also greatly impacted my relationship with my boyfriend. The selfish part of me wants him to not see her anymore, but i know I can’t ask that of him. But every time he does, it’s extremely hard for me to deal with. I feel that once we get married (we live together and operate as a team/married couple) you cleave yourself from your family of origin and make a new family to hold above all others. I feel betrayed when he sees her because of what she has done to me. How do I deal with this? How do we deal with big events, like a wedding and all parties associated? Holidays? Kids? I feel so heartbroken and angry. I’m not sure i can do this for the rest of my life. Nothing will ever make me stop loving him, but I don’t know if I can be excluded for the rest of my life due to his family and him needing to spend time with them (which of course is expected and fine.. it’s just my hurt from his mother) What do I do?