No you can't divorce him and he can't be removed from your birth cert, but you could change your surname by deedpoll. I did aged 18, to annoy my dad (I know that sounds petty) and to prove to him that I was nothing to do with him. You could also change your phone number/email address, tell him you want no more contact and stick to it.
Look into getting a restraining order if he really is ruining your life, but they're not cheap and you may need to prove he's harrassing you.
Good luck, theres too much pressure on people to get along and stay together just because they're family, but I know only too well how poisonous these relationships can be, and what terrible effects they can have on a persons life. I haven't had any contact with my dads family for nearly 10 years (I'm 24) and it feels great! Esp. knowing they can't ruin my little girls life, like they tried to do to mine.