Do I have reason to be upest? How should I approach?

long story short, this guy & i have known, talked & liked each other for awhile. we never talked about being bf/gf but i see that's where it's heading, BUT one thing i think is getting in the way is this girl he supposedly visited while we were friends (but he knew i liked him), saw a pic on his myspace making out w/her and since then have been kinda weary about her making comments on his myspace. I've confronted him about it & he says that she is just a friend & doesn't like him like that, but her last comment she made makes me think different. He tells me he loves me & i tell him i love him, but my feelings are always confused because of this girl. How should I react to this? Because it makes me infuriated that he is still talking to this girl & now I just found out he went to her city & visited her! He tells me not to worry that they are just friends & she is going in a different direction which makes me think he has or had feelings for her. I just talked it over w/him & he says me & him are getting more serious & he is working on dealing w/her, I guess ending being so friendly?? I need opinions because he showing strong feelings for me & seems jealous that I might have other "potentials".