I understand how you are feeling. My abf lived with me. For the past several weeks things have gotten worse - everything....our fights, his drinking, his not being able to work, his sleeping more, and of course.......the worst (imo) -- another woman. This isn't his first he did this. I forgave w/o asking him to move every time but once. I always asked him why he just didn't move out and then have the affair. Or move out now if that is what he wanted. Working towards our relationship would always be damaged even after I forgave him because I no longer felt the desire to be intimate with him. I didn't want to catch anything and also wanted him to really want to pursue me and make me feel important. I think he thought just his being here should make me feel that way. My trust in him was gone too and I felt it was up to him to gain it back. he never wanted to "work" toward that because it is not "fun."
His way of seeing it "I was drunk, I would have never been with her if I wasn't drinking or wanting to drink more." That never made me feel better because he is drunk most of the time so how could trust him most of the time. Later he used the excuse "I had to get away because you were bitching and arguing with me all the time." And that just wanted to make me bitch and argue more!!!
Now Dodge, that is just me venting. I feel bad you are having to deal with all this - plus with a baby involved. Do you have friends and family to help you? It doesn't seem you can count on him. My guy would always lie to me ...even when it was so freakin' obvious, such a see-thru lie. Then he would get angry for me calling him a liar!!!! What is that about?!!? The lies were insulting because I felt he thought I was that stupid that he could just lie about whatever and I better be ok with it. Just hurtful things.