desperate for advice!

I don't know whether this is the right group to post in but the others don't seem to have this topic pop up either..
I'm 15 weeks pregnant with my little one and have finally plucked up the courage to end my relationship. Reason being: ever since I found out I'm pregnant my (now ex) has done nothing but make me cry, get angry, be controlling, show aggression and be a general arse. I have recently found out that it's not only me he's been like this with but also previous exes who actually had it worse off than me cause they didn't get out sooner. From what I've been told he is a fruit loop and isn't right mentally. He's stalked his ex for months on end after they'd finished and also showed physical as well as emotional abuse towards her. He has a sick way of twisting things around to make you look like you're the bad guy. He's even called me the emotional abuser, torturer, evil and told me I'm committing slander! Which I'd never be like to anyone regardless of whether I disliked them or not. I'm just thankful we haven't moved in together because everything would be ten times worse.
After finding all of this out it has scared me beyond my control. I have a little boy who's about to turn 2 (not his baby) so him and my unborn are my main priorities. What would you do in my situation? I obviously don't want to stop my child from seeing their father but I have a feeling he is going to make my life hell. I'm going to be seeking legal advice and general advice from social workers etc but I'd really like to know your views and opinions because it may be very helpful. Thank you in advance!