My husband left us...?

I guess he was miserable with me so he moved out one day while I was at work... He has been teeter/totering with me and I have no idea what to do. I obviously do not want a divorce, I want to at least try to counseling and working on being a better couple - but he doesn't want to try. He is staying with a couple friend of ours. Although I am thankful that they've allowed him to stay there - the majority of the time the guy is away for work, so it's just my husband and a female living together - That situation makes me uncomfortable. Also - I know one reason he's unhappy is that we just had a child (he's 5 mo) and my husband had to "give up" certain things like drinking all night, etc. He wasn't ready to do that. Now, he and this couple (more often just the gf) as well as he and his friends go out and drink all night. I'm starting to blame my 'friends' for allowing him to stay there while he walked out on us, and encouraging him to party all the time.