What can I do?

So my boyfriend of three years starting next month, cheated on me once again. I found out a couple of days ago because I had a strong gut feeling something was wrong. He wasn’t acting weird or different I just had this feeling. I’ve had these feelings before when he’s cheated on me and I was always right. So I trust my gut and when he went to shower i went through his phone and found nothing except his one incriminating thing he sent to this girl that was supposed to be his “friend”. They dated at one point along distance but it didn’t work out. Back when I first found out about her I added her on social media and ask her how she knew him if they were friends that’s cool. I’ve come to trust what girls tell me a little more than what he says so I always go to them first. Well she was rude and shut me down before I could even say anything really. All I asked what how she knew him and she asked if I was his sister I said no I’m his girlfriend. And then blocked me. Later on she apologized and we became okay. Then I see her name pop up on his phone and then that night get his phone after a calm talk and go through it but I hadwent through it before without him knowing and I saw he deleted stuff that would’ve gotten him in trouble. But I just knew he would cheat on me so I let it go. Hen a couple days ago I got into his phone and saw him saying something gross to her. I blew up on them both. And found out they sent nudes the night me and him talked and I went through his phone. I had went to a friends house that night too, so he cheated on me after I accused him of cheating.. funny right? Well I had his phone hacked all his accounts some he gave my the info for some he didn’t. And it turns out he cheated on me the day after I caught him the last time last summer. After I got his account form Pornhub that he used to cheat the very next day he made another one and another email and another kik account AND Snapchat just to cheat he had done it all the way up to the morning I caught him. I felt humiliated at the pictures I saw on his dropbox. They were all Pornhub girls but still. It hurt. He spent money on this girl while we’re struggling. It was $5 but still... but the girl, that started this along with him bc it takes two, I saw her pictures and it made me sick. I knew she still had a thing for him bc back when she apologized for being rude to me the first time she admitted to trying to take him from me and sent him a pic in her bra. So I was suspicious the entire time they were friends bc he knew what she said I told him. So what do I do?