I need some relationship advice?

ok ive been dating this girl for half a year and we (i know it sound might sound naive because im young so im automatically naive) are really in love, they're have been moments when we've broken up but only for a couple of mins because i made promises to change and i have and kept them all. And back when we first started dating we had a group of friends that we hung out with (and she went out with them because i didn'tnt know her and shes a year older than me) and they stopped being friends with us because they're was a rumor i ate her out. (lie) and now they've started being friends again (not with me, with her) and so she could see them she stopped hanging out with me after school and hangs out with them now, and im nervous becauses she dosnt wear her jacket around them, and i kinda feel as if she is trying to flaunt. And she hangs out with them longer than she usually did with me. i just feel unwanted now and kinda betrayed like she chose them over me, esp since half of them are her exs, i feel like crap, but i just need some help on how to calm my nerves becauses i know she dosent do anything, but of course im very insecure, and im willing to stay with her even if i feel horrible. I really really want to spend the rest of my life with her. Thanks for the help, please dont try to rip too much on my insecurity and my feelings for her. Its just me. Thanks.