Whats more important?

Right kinda getting annoyed how my fiancé likes to tell me last miniute things to go out to see his friends. He's just came off the phone too me and asked if he can go and see his best pal at the pub as he's not seen him in 3 months. My fiancé knows I'm pregnant and is very aware that I'm due in 23 days so I can go at anytime. He can't handle drink but promises this and the next thing. last time he was out he said he would be home at a certain time as it was his works night out but didn't come home till 2am and a little tipsy. The week before that he met his dad and brother and got that drunk he ended up in hospital due to him collapsing and getting adrenaline shot. He's 21 years old he's just did a 9 in a half hours work he's just about finished and asked me at this time at 10.50pm to see his pal when I know he won't just go their and not have a drink cause he will want a pint. My family have warned him and last time he was out he was upset cause he lied about having 1/2 drinks but had more than that and i had to phone on that night about 20 odd times as I got no reply cause he said he would be home at 10ish but ended up in a pub and night club and coming in at 2am telling me he was on his way (imagine lying to a pregnant woman about coming home). I know he's wanting to enjoy himself before he becomes a dad but he has responsibilities and he's expecting a baby. I love the guy to pieces and don't want to lose him

What do I do? Say? Advice would be appreciated