Hi there bigchicken and welcome to HW
Seems to me that you have had a rough 25 years..
And now it could be time to take back a little control in your life and start working towards feeling better.
Ok, so now you have to face your father on a constant basis because he is the caregiver of your mother...sheesh that's gotta be difficult for you..but hey, you Are coping thru all this even tho he is putting you down etc...and that tells me that you are stronger than you think!
Abusive people thrive on the 'reaction' of others...by not taking the bait and biting, or turning into the complete victim at the smallest remark you take away his fun - once he realises that you are not gonna play this game anymore he will soon become bored believe me it works lol..
Counselling/therapy is a great place to learn skills for coping with this sort of thing..I wish you well and think it's great that you care about your mum and are being sooo brave about all this regardless of your feelings towards your father.
Take good care and keep us posted.