<human>: My boyfriend, who also happens to be my best friend, is a really wonderful person. He's very honest and open, and always expects the same from me. He has done nothing to make me doubt his trust. 

He's had female friends throughout college, even female roommates. Again, within those relationships it is very obvious that I have nothing to worry about. But I do. I really try not to show it, because coming off as the insecure/ jealous girlfriend is in no way admirable. I also understand that anyone I date will have friends of both genders, just like I do, and that not everyone is out to ruin my relationship. 

Last week my boyfriend said he is going to meet up with a female friend he hasn't seen in a while, just to catch up and spend some time. Upon hearing this I had a bit of an internal meltdown. Why? I don't know. There is no good reason. I tried to keep it together, why should I stop him from seeing old friends? I think not knowing her is what is making me the most insecure. My mind is cruel, and I always imagine the worst of what I do not know. After some facebook stalking of this girl, the meltdown continues. She is insanely beautiful, like what-the-fuck pretty, and knowing my boyfriend, she's a cool person too. 

The level of insecurity I feel is tearing me apart. Obviously this is a reoccurring problem I struggle with, but right now I am feeling especially terrible and anxious about him seeing an old friend. I would like to clarify that I really would like some advice as to what I should do. This is really a ME problem, and I feel like I shouldn't be adulting in this fashion.

Condense the text into a few key points
<bot>: Boyfriend is very trustworthy, but when he hangs out with other girls I feel very jealous/insecure. He is going to see an old female friend next week and I am freaking out, how can I change my thinking?