Boyfriend issue

Ok guys so here's my problem, my boyfriend currently lives in Texas and I live 8 hours away from him and this weekend he came up to see me and his parents but he bought this girl with him and claimed she was a friend. I decided to brush it off my shoulder so I didn't ruin the trip but now that they're both back in Texas I'm freaking out. He said he was laying down with her and watching Netflix, he said he would never cheat on me and that she's just a friend but what should I do?