Should I trust my gut? Did he cheat?

A year or so ago, my boyfriend and I were both in college but I was an all online student and he was on campus. I missed being on campus so I’d always ask how class was, if he made friends, or if there was anyone in his classes he got along with but he always said no.

fast forward a few months and he asks me to get on his phone to read him a message from another student. I do, but when I finish I see a tab on the app used by the school that said “secret conversations.” I click on it and see a girl named MyKayla. She was sending messages saying “help please come find me 😉” and he had replied something along the lines of he was In the car and he would be right there. When I read it, I didn’t say anything, just turned and asked him if he had made friends yet and he still said no. I asked if he talked to anyone in class- he said no. And when I told him I saw their messages he started denying everything. I had him leave the house and he went to MY sisters to tell my whole family his side of the story before I could even call them. I also looked on his Instagram and he had skipped watching and liking my posts and went to hers, AND had added her on Snapchat.

I let this blow over and a few weeks later we had another argument because she asked for a ride since “I’m just a neighborhood away from yours” I asked how she knew where we lived and he said they had to say where they lived during class ice breaker activities.

I still think something weird was going on but he still won’t admit anything. Should I trust my gut?