"Better the devil you know?" comes to mind after reading your post.
"Misery likes company" does, too.
My father was only happy when he was angry, and lashing out at us, and he really was a bad person, but I don't see that in you. He never ever showed any remorse for his behavior, but you do. You are seeking help and support, which is a very good sign.
In my opinion, it's not necessary to be too nice to people all the time; just be yourself unless you're like my father who kept that hidden from the public, but took it out on us, in private.