Please help me figure out how to move on

Without going into too much detail as it would be a book rather than a post, COCSA, both parents substance abuse throughout childhood, mother still alcoholic. Emotionally immature. Siblings with lots of serious medical issues.
Since first challenging how my mother spoke to me / treated me when I was in need, there have been years of cycles of being half ok and then pulled back into arguing. I will admit at times I’ve been as bad as her in how angry I’ve become and said things at times I shouldn’t have, but I have never said things others thought about her, only my own experiences and things she has said or done.

If I bring up a behaviour of hers or an incident or nasty things she said, she goes on the attack, pulling up things from my childhood. She uses a manipulative tactic of telling me negative things others have thought about me and my kids, damaging my relationship with them (all the rest that does to a person raised as I was).

I’ve recently cut her off entirely, but in the last week both my aunts have been in contact and my mother and father have both contacted my brother as she is crying constantly not sleeping etc. ( I have experienced this for years because of her and when I told her before I’d been suicidal she told me I wasn’t the only one who had problems and I had it good and leave the past in past basically).
No matter how much I know it is best to have no contact, I totally emotionally collapse when something like this happens. I’ve been crying for hours for maybe the 5th time this week. I’ve done therapy before and will go back when I can, but HOW do I stop the wound opening up just as raw if not worse every time this happens?!?
Please any of your own experiences and wise words would be great.
I do not want her to hurt, it breaks my heart knowing she is hurting like this but I know by this stage we will never get from eachother what we need to move forward. This most recent time, I had honestly put so much or it behind me an healed, thought I was building a good relationship with her, finally enjoyed her company only for BAM out of the blue while she’s drinking I disagree with her on something and she attacks me and hits me with someone else( who is one of the only sources of real support I have) also agreed with her how difficult I am. It cut me to pieces.

I was also really wound up and overwhelmed and snappy with my kids and husband today as I had to go to a funeral she was going to be at, and this is the exact thing I don’t want - in those moments I was verging on being her, I saw the patterns in my behaviour and did the work to stop it but sometimes when I’m super stressed they come out and I hate myself so much for it - I took half a diazepam in the end before leaving for the funeral.

Please help?