Forum | Is my ex worth it?

I've been in a relationship for almost a year but I haven't been happy in it for awhile. Guess more afraid of being alone more than anything but I have a 6 month old son but it's not my boyfriends but we call him his dad. Well an ex from almost 3 years ago contacts me and he was the guy I had sex with for the first time and he ended up really hurting me. The first day he contacted me, he acted like he really wanted me back and i resisted because I'm in a relationship. I still care for him a lot but now that I show that I'm still into him he doesn't show much interest. His attention is really grabbed when talking about sexual stuff. He's also in the navy and just got in there. He told me he wouldn't be able to see much and it would be a long distance thing. He wouldn't be sure when he could see me. Now I'm stuck between a year long relationship that I haven't been so happy in and one that I'm not even sure it's worth showing any interest in. I don't want to be just someone to keep him busy because he's lonely over there and sexually mad. What should I do? What can I do to make sure he isn't just using me and going to hurt me again?