IT'S CRAZY BUT PLEASE READ AND HELP

I might sound crazy but just bare with me .My bf and I have been together for 2 year and now I relationship is unraveling the beginning-middle was my fault I was still talking too people who I use to date an even when he asked me to stop I didn't but we had a falling out (he had to fight someone over me it was my fault ) and I realized I love him now where here were he is doing what I once did along with talking too new people .I left town for a week and while I was gonna he was barley answering me always saying he's busy so I come back and find out that he's texting a ex and and he was asking here to come over several times and if she was going to come over and get naked for him .....his response when i asked him was y are you in my phone and it wasn't me that someone had his phone but the messages where from 10am till 7pm with time gaps in between but still there's no way in the hell someone had your phone off and on texting someone and you didn't notice any who ..next day I put a pic and his IG page later next day I'm on his phone and his ex dm him saying i can't claim you if she claiming you and his response to that when asked was she was asking if him andbi were serious and she was trying to get him to leave (lie be up she knows were together and even wanted to have a 3sum) and last where here .Tonight someone is blowing his phone up at 1am so of course I'm a go check so i pretend to be him and act like I don't know the girl and in the conversation she told me they met on pof he came over to her house an they messed around so I calm my self down and wake him his response...he gets mad and doesn't want to explain it get pissed because I went thru his phone again I said I wanted to be single we got quite he broke his phone and asked me if I really wanna be single and I told him to tell me the truth and he refuse too..WE'RE NOT TOGETHER ANYMORE and he's acting heart broken and for me I'm chilling .I need advice as what to do