Am I Too Jealous?

I've been dealing with a lot of emotions regarding my guy lately, and I can't talk to him or my mom about it, and I have no friends I trust enough to keep this quiet, so, I'm venting here.

I don't have a lot of friends... hardly any, really... and that's rough, because I love having friends. As of late, my guy has been hanging out with this girl who used to be friends with me, but now she just ignores me. For example, he and I were shopping and she came over to say hi, but didn't even acknowledge me. And she goes over to his house every now and then, and tonight, they went for coffee and a walk. He and I have never done that. I am super busy, so I take that into consideration, but he doesn't see anything wrong with it. like, he would totally be okay with me hanging out one on one with a guy. I don't doubt that he loves me, but I'm worried he'll find her more easier to get along with. I'm also worried about her intentions. I don't trust her one bit (then again, my experiences with girl friends haven't been good). Am I totally imagining things and smothering him? I want to be a good girlfriend, but I do worry...

I just needed to vent...