Engaged and heartbroken

Ok so I’ve been with my fiancé for 3 years now and he has trust issues due to his last relationship but now he’s acting if I’m a cheater. We broke up for about two months he got back with his ex and I started Texting a guy. He found out about it and I lied but we weren’t together so idk why I lied to him about the guy. Now that we’re back together he don’t trust me but I found him still texting and sending money to his ex claiming it’s for their child but he don’t trust me and he deletes all their texts since he knows I be going through his phone. I really love him but the things he’s doing really hurt me. Then I looked at our phone records he be on the phone with her for hours and hours at a time saying it’s his son which is three and I’ve been around him when he’s been on the phone with his son and they never be on the phone pass 10 minutes on FaceTime and now he’s saying he talks to him on the phone for hours I just don’t believe him .What should I do call off the engagement or try to work it out ?