I have no idea what to do... Drunken POS (pretty long)

Alecia • Living the good life here in wonderful Colorado! Expecting my first! Beyond scared but wonderfully excited! So. Much. Love.
The relationship with my SO has never been easy to say the least. Not that I'm pregnant (24 weeks) it has become even more difficult. Before becoming pregnant (not planned) we went out a lot to the local bars. It was fine when I was drunk with him. We always had a great time. When finding out I was pregnant he really pressed me to get an abortion. He has a five year old son with his ex wife and really didn't want another kid so soon (I'm only 23 and he's 25 so we are young). Once I knew that I couldn't go through with an abortion and decided that I wanted to cherish this pregnancy and keep my baby I gave him the option of not being in our lives if he chose not to. He got mad saying that's not the kind of man he is. He slowed down on drinking but still goes out once in awhile or has drinks at home. Yet every time he gets drunk he comes up with something to get absolutely livid about. Usually for no reason. It has been going on and on and usually threatens to leave or does leave. I try to deal with it by trying (usually failing) to calm him down or just by simply walking away so we can deal with it when he's sober. Yet that usually sets him off even more. Now he works at a local bar and hasn't been getting home until 2,3 or 4 in the morning. The past 3 nights he has come home wasted. Tonight he came home, I woke up like I normally do and of course he's wasted but everything was fine. He was being nice and lovey dovey and starts trying to have sex. I give in but he's wasted so it's sloppy and he reeks like booze. Obviously not something that attracts a woman, much less and pregnant woman. Yet I don't say anything and continue to let it go on hoping it's over soon. Eventually it starts hurting, I mean down there for a pregnant woman is sensitive. So I ask him to stop and try pleasuring him other ways. After that fails I give up. He says it's fine and that he understands. Yet acts pretty upset (our sex life is pretty regular so it's not like this is the first time in forever). I apologize a few more times and then all the sudden he starts freaking out. Saying it has nothing to do with the pregnancy, that this is just accumulated from everything that's wrong. I try to explain to him that no it isn't. Number one its 4 in the morning I'm tired and just wasn't feeling it anymore. Not to mention it was taking him forever because he was drunk. I walk away and go to the bedroom and shut the door because I'm not going to sit here and have him yell at me for what I feel is no reason. As I'm walking away he says 'oh there you go just walking away like you always do. Ya know usually the person walking away is the one that is wrong.' I'm just thinking, no I just don't want to deal with this now. He proceeds to go around the house and pack all his things (we are house sitting for my parents so it's not a lot) and gets in his truck and drives away (yes drunk)! Before he left I said that I love him and he says 'oh yea do you?' I say of course I do and he is the one deciding to leave. He says no I'm basically deciding for him and I tell him that I'm not going to sit here and beg him to stay (keep in mind that this is like the 10th time something like this has happened so I'm just over it) and he says well maybe that's the problem. Like he's telling me I should be begging him to stay. The worst part is that we JUST signed a lease to a new place yesterday! Now I'm just thinking what the hell am I supposed to do!? I can't afford a $900 rent by myself especially when I'm pregnant and barely working right now. It just seems that every other thing that happens, every other day he is threatening to leave. I just feel like this is obviously what he really wants since he threatens to leave all the time. I just don't know what to do. This is why I gave him the option to leave when this pregnancy first started. So I wouldn't have to deal with this when I was 6 months in. I just feel that after tonight he isn't going to come back and honestly that is fine because I am so so over this BS. Especially because it started as nothing! I just don't know how I'm going to do this on my own. I'm sorry for how long this is. I guess I just needed to rant and get this off my chest, even if it's just to women I don't even know. Anyways thanks for reading.