What do you make of this situation? please answer..?

So.. I have been dating this guy and he lives with his baby mom who he broke up with a couple months ago because she cheated on him with his brother.. He lives with her still.. but swears they have nothing going on.. What happened was he was drinking with her at their house and I told him it bothered me a bit because I too have a baby dad but would not drink with him out of respect.. So.. he tells me he wont since it bothers me.. But then the next day he callsme and expects me to get a sitter because he wants me,the ex and the exes best friend adn himself to go drinking.. well i couldnt get a sitter.. but my baby dad was coming over later to visit so he watched her for an hour while I went and said hi to him and his ex and all..The whole time I was there he barely talked to me and stood closer to her and shared smokes with her and not me.. sounds juvinile BUT still.. and as i was leaving with a friend of mine he barely acknowledge it he was busy sharing head phones with them so i didnt even say bye.. and today when i call to get a hold of him cause hes suppose to meet me at three.. they say he doesnt want to talk to me cause i am a crazy *****?? But I think i have reason to be upst about him drinking with her? So now he doens't want to date me because I got mad about their friendship because i do not understand why they have to go out drinking togethr when they already drink at home together.. kind of odd to me.. SO what do you think? He must still like her right?