<human>: Condense the text into a few key points

So I have been on a long distance relationship for 5 months in a 7 months relationship. His best girlfriend is coming to his city because she has a party to attend and she is going to stay at his place.

I trust him with all of my heart but I can't stop feel jealous about it. I don't know her but he mentioned her to me a few times and I know she is his best friend for a long time.

I know I should be okay with it and this is a silly feeling but I can't help myself. What should I do? Should I tell him that? I feel like this is going to make him so upset.
<bot>: Old friend (girl) is coming to my bf city to spend the weekend to go to a party and is going to stay at his place. I am feeling jealous.