Very harsh feelings toward my father.?

Just move out. Then invite your mom over for a few weeks, let her experience how is it to live without your dad. Your mom did so much for you, you owe it to her to get her out of that atmosphere. If you do not have the means, talk to your bro, get part time jobs and get a house together and take your mom away from him. But remember, it is hard to live without a partner, so maybe that is why your mum does not wanna divorce him. So just do your mum a favor and for like two weeks every month get her out of there.