I don't know what to do??

so me and my boyfriend , if you can call him that , have been together for 4 years . but we haven't actually been together for the last two . we've had a pretty ricky relationship but I've always stayed to try and make it work . around Christmas last year I found out he was talking to other girls and telling them how beautiful they are or how he wants to do certain things with them and when I confronted him about it he just kept saying he didn't meet with anyone and the majority of the time he just wanted someone to vent with and that I didn't care at the time . but I ended up just letting it go and try not to think about it . But we still aren't officially together either. recently he got sworn into the marines and I'm over the moon happy for him but I keep thinking how are we going to make it through together if we aren't even officially together . I want to be with him and today for it being national boyfriend day I asked if I can post a picture of us two and write an appreciation post for him but all he said was not to expect the same thing from him . I just don't know what to do anymore ?