Friend Issues

Hello! So suddenly one of my best friends suddenly never wants to hang out with me anymore and is always hanging out with this new friend, and I'm a little jealous but don't feel like I deserve to be. Me feeling jealous is just making me feel like I'm being selfish ya know?

And what really started it I suppose was that me, my little brother, my friend, and her friend were supposed to go swimming one day but canceled last minute cause her mom said that she shouldn't stay up too late 2 nights in a row, which is odd cause she's never cared before and has never said anything like that. But despite me and my little brother not going to hang out my best friend still went swimming with the other friend and did another thing with them that night and it made me feel like I was slowly loosing her. And now every (almost) time she sends me a picture on Snap it's always with this new friend and their always having fun. It makes me think that I'm not good enough and that she doesn't enjoy me around anymore.

Does anyone have advice on what I should do? I know though that I can't talk to her about it because a whole fight is gonna start and shit.