relationships after being cheated on

Me and my male best friends boyfriend both got cheated on in the past and I realised how we both behave the same way. Toxic ways. Like the need of control over the relationship. I sometimes check my boyfriends phone, I try to stop, but I'm often curious about how his friendships are. My best friends boyfriend even checks my friends phone 24/7. I really want to change my toxic behaviour and trust again. But idk how...