damn, sounds like my mom, she needs to get help and talk to someone, maybe get your dad and family and do a family meeting and talk to her...i know how you feel!
menopause could be the cause. stash some chocolate and offer her some when she gets upset.
I know it's not an excuse to be abusive, but are there things going on in her life that might contribute to her behaviour?
Lol, my mom is like that too. She gets so violent sometimes.