Couples who suffered infedility, please help me.

He didnt sleep with this woman, but they went as far as sexting and sending each other nudes. She was well aware of me and contiued. This goes back from september ( im basing this off the dates on txt messages and facebook messenger). He left early morning and forgot his phone. I went through it and saw it all. I confronted him with his phone in my hand with this womans vagina picture. He was too embarassed and didnt even know what to say to me. I immediately told him our relationship is done. We have been together a little over 3 1/2 years and have been talking about kids in our future. He later that day told me , it was his ex, he has supposedly sent her a message saying he wants nothing to do with her. He went on to say he is embarassed and hurt that I had to see that, and it was all in fun for him and that he had no real intentions with tjis woman. Let me remind you that he and her have history. They even shared I love yous. 💔 Im struggling with the though that this may not be fixed.. Im reaching out to anyone who has gone through something simliar and maybe shed some light on what is the right thing to do. Im embarassed to say this but we have been intimate. We still arent together but have been living together for 2 years. I feel like every time he gets a message or is on his phone, I now wonder if its another woman. I feel like I cant tell anymore if he really does in fact love me or not. I feel like im neck deep in this relationship and he isnt. 😞 I need guidance , please.