My bf's childhood friend

So my bf has this childhood friend and she is a girl and they have dated before like twice and when i was hanging out with them and two other friends my bf had to change his shorts so we went into an ally and when he started getting dressed i said "nobody look at my bf" half jokingly and so i stepped infront of his childhood friend and she kinda was pushing me out of her view and she said "dude ive seen him dress before" and my bf said "yea im use to it, its fine" and that really pissed me off and the thing is she likes him and my bf knows that and there have been other things to like when she sees him she runs and jumps on him and she hugs him and uses his jumper and i just dont feel important to him and i have told him it makes me jealous i just dont know what to do.