Lost...

So there's this guy... And we've had a thing for a while... starting in July of last year... but we had some really bad bumps... we cut everything off only to come back to each other again... he's the first guy I ever told I love you too. We were good and everything and were even engaged... then we broke it off because he's in the marines and it was getting stressful because I was suppose to be going in but couldn't. And it was just a giant mess. So we took a break, and when we started talking again we decided we should just try to be friends. Well that didn't work out and we got Into a huge argument and we just recently started talking again causally. Only problem is, he has a new girlfriend . And I'm happy for him, because he's happy, but it hurts me... And he just told me tonight that he misses me and still wants me... I don't want to get attached again and get hurt all over again... What do I do...?