I don't know if this will help. But I was kinda in the same boat as you.
My mom was a whore who slept around while my dad was overseas, then up and abandons me...
setting it up for my dad to abuse me later.
I spent my whole life HATING her...wishing her dead.
But right as she was dying from cancer, I got to see her again.
I felt pity for her, for the life she had created for herself.
I am just now dealing with the feelings from when I was a kid and she did all the things she did. Cause when I allow myself to go back to little Buzz, I remember her being loving to me and me loving her back----and think, why did it all have to go bad?
I guess my point is this...we are ALL shaped by others....what shaped her? What is her story?
I don't mean to make excuses for her actions -
You do need to take care of yourself first...then if there is room...deal with your mom.
I'm sorry for the crap you went through and still go through.