<human>: Could you distill the essence of the text into 1-3 sentences?

Saw a suspicious text over his shoulder and then did the bad girlfriend thing of reading through the conversation in his phone when I had a chance.

He slept with this girl while we were broken up ( 2 weeks) while he was provinces away ( for 2 months) for work. He constantly travels for work, I never worried about it, until now. Claims it was a one time thing but it doesn't sound like it to me. I learned all of this after asking him to leave my apartment and never come back

They were both flirting with each other, her (provinces away) telling him to get a house with her, how much he had been on her mind lately and wondering when he would come see her next. Him calling her all the names he calls me (gorgeous, darling, sexy etc), telling her he wants her naked under him, would come see her next month and of course would make time for her, that she was good for his boners (barf) and that she was giving him a semi (double barf). That she should "get on a plane and sit on my face" Most of these conversations happening in my apartment, in my bed while I was asleep beside him.

He says it was inappropriate but harmless. That he had always been faithful. We got together because he wanted commitment, he pushed it on me. We started saying I love you a couple weeks ago, again because of him.

Did I react too harshly? Should I believe that it didn't mean anything and he just felt bad for her because she was lonely? Should I stay strong and stay broken up with him?
<bot>: Found sexts and what looks like a relationship on my SO's phone. He denies significance. How should I read all of this?