Caught my ex in a lie and another one

I was just spending on what I thought was a great evening with my ex boyfriend and I am now sitting in my home at my desk crying and feeling utterly devastated. We split up about 2 weeks ago maybe three because I have insecurity issues and abandonment issues and rejection issues and trauma and I'm trying to work through it all but my jealousy sometimes gets the best of me. He has over the last 3 months developed quote unquote friendships with random women that I have never met never seen and they come over to his house at 2 3 4:00 in the morning and get undressed and climb in his bed and stay there for 2 or 3 days. I felt it was disrespectful but because we were broken up he wanted to have his friends and his friends were that important to him that he had to break up with me because he didn't want to hurt their feelings. Tonight while he was in the shower, I opened up his phone to try and see what he was doing I'll be honest I was snooping. I wanted to try and see if there was any proof for evidence of my suspicions and I I had no idea what was in there. I saw messages too a couple of his friends messages to me and a number I didn't recognize i. I thought it was his mother's phone number but it didn't look right so I opened the thread and read through it. It was not his mother. In the conversation, he and this other person we're talking about the last time they were together intimately when was she going to come back and spend some time with him so they could do it again and then he asked her to come and live with him and his new apartment because he loved her and he missed her. She turns him down for the moving invitation but said that she was really looking forward to the next time they could get together and have sex.

I closed his phone up and set it on the table, got up got dressed, and he came out of the shower and asked me what was wrong I guess my facial expressions or body language was communicating that I was deep and thought about something or something was wrong with me. I told him that there was nothing wrong I was just tired and then I left about half an hour later. This all happened about an hour ago and I don't know what to do now. I can't respond to this. I don't know if I'm stuck in beer and that beer flight fight mode but I do know that I am completely devastated by this. He swore on his children and on his mother and on everybody all that he held dear that he was not seeing anyone else nor was he sexually active with anyone else he wasn't cheating he's been vehemently arguing with me claiming that my insecurity about his infidelities or I'll just meet up and result of baggage that I have from past relationships and then I was a bad person for thinking about that thinking that about him. At this moment I feel like the biggest fool I am hurt I'm scared I'm angry I'm disappointed and I don't know what to do next. I feel like I want to just have no contact with him anymore I don't want to be friends with him at all. I can't trust him and I can't find a reason to learn how to trust him. For the past 3 years we've struggled keeping this relationship together, but we felt that we loved each other enough that we could work through all of our problems as long as we were honest completely honest. And now this..

Is walking away the healthiest thing I can do, severing all ties to him and not going back ever? Do I confront him and forgive him if he says he's sorry? Am I supposed to believe anything he says anymore? How do I have not internalize this? He did the exact thing that he swore he would never do my last three relationships were marriages and they all ended because my spouse was seeing someone else and completely dishonest about it until 3:00 moment when it was most convenient for them to leave me. I feel stripped down to my core naked beaten betrayed...

Please help me find a healthy perspective on this and suggestions for a solution. I don't think I want to be with him any more.