How to detach from a guy

Please no judgement. I have been “dating” a guy for almost a year. We talk from the moment we wake up to the time we go to sleep if we’re not together so he is already part of my routine. Our connection feels out of this world, im 29 and I have never had a connection like this with anyone we are laughing 24/7. The issue is that I would get insecure over his bm, every time we had an argument I would tell him that it was done and he would go and sleep with his bm thats when my trust issues with him started cause it seemed like he wasn’t done with her & he’ll tell me that it was just sex, keep in mind she knew about me. She knows that he wont get back with her because he wants to date me so she’s okay giving it up to him. I know this isn’t something I wanna deal with so I literally blocked him off everything but I crave his attention and im so scared to give in 😭😭