Have you ever been cheated on?

Tey tey

.. if you Have, how did it end? Did you and your SO get passed the cheating and stayed together? I'm really lost right now and I don't know what to do. I love him. But.. he betrayed me. He said it was only once and only with that one girl. I found out because I opened his phone (I wasn't purposely looking to snoop or anything. I was just opening his phone to call my older sister) and it opened to this chat. I thought nothing of it until a message popped up saying "baby are you there I can't sleep" and I thought what the fuck? So.. I scrolled up. Bad decision. So much dirty talk so much flirting and 'teasing' if you get what i mean.

All i could do was stand there in shock. I couldnt believe it. I still don't want to believe it. Him and I have never had any arguments, fights, or problems. At least to my knowledge. We we're just having a party at our place and he was quite drunk. And all I could say when he walked into the room was "Who the Fuck is she." I was crying so hard.. theres many other details and it's just so much. He said it had only been going on for a week and he apologized over and over and promised to cut ties with her.

I want to move on from this I want us to fix this because I love him. And he said he wants to fix this.. but i guess what I'm asking is: is it even possible? Am I just stupid? Please someone I just need advice I have no one to turn to.