ex to the next.

So me and my fiance/son's father split up. he's always been very mentally abusive and I finally snapped and left him. Well, we are both still currently living in the same house because our landlord was giving us a really hard time and also low on money it would be hard to just pick up and go. So I've been talking to this guy and he is the sweetest. always showing interest on anything I talk about. always showing concern to see if I'm okay or sleeping well or anything. and he always talks to me like a queen. I've never been treated like this in anyway and it feels so nice. but I don't know what to do about my ex. Hes continuing to be mentally abusive and draining. He's been begging for me back even though I told him no matter what I don't want to come back after I say this he always gets mean. ladies any advice on what I should do at this point.. :( I'm so mentally drained and just want to be happy finally but he's still holding me down...