Where to go from here about bf lying?

Hi all,

My boyfriend (28M) lied to my (27F) face about some things he did while he was away with his friends to go to a festival. He told me that he didn't link up with any women or that nothing really happened other than he met with a few of his guy friends. No mentions of girls. I had an inkling (recurring dreams, signs, etc.,) so unfortunately I did go through his phone. I saw some messages on IG showing that he did link with a girl and her roommate and bought them drinks.

I confronted him about the messages, even though I didn't want to, and he lied about them both times. When the truth came out he swore that nothing happened and it wasn't important enough to mention. He said that she was a friend from school ( which I never heard about) We both got mad, him bringing up a similar situation where he felt uncomfortable with some things I did/ messages I had in my phone way earlier in our relationship. We'd gotten over everything and we were doing so well for a while, no arguments and fights. We are pretty much bread-crumbing each other/no contact. I am pretty mad because I just have to go on his word that nothing sexual happened. But he lied about it. So I genuinely don't know how to feel or what I should do.