I just want to add that she's been really caring and supportive towards me in a lot of ways, even going so far as to try and set me up with dates.
Writing the above post I realized how much of this I haven't discussed with her yet. Most of the negative feelings came up since she moved out a week ago, and I haven't seen her since, and though we chat online quite a bit every day I don't want to talk about this on chat. Especially when she's in the room with one of the other guys in question.
We're getting together tonight and I want to talk about it with her. But I'm also worried that if I tell her about these feelings that I'll seem needy and pathetic which has ruined some of my past relationships. Neediness and jealousy after all tend to be huge turnoffs especially for women.