My Boyfriend's X

Ok. So I've been with my boyfriend for over a year now and we have a child together. But we've known each other for almost 4 maybe 5 years. And the majority of our relationship I was pregnant and he put me through a lot of stuff. We broke up but always got back together bc I love him. And I never wanted to give up on having our family. But his X just won't go away. We used to always argue and fight bc she would text him and call. It wasn't just a grind checking up. It was more. She was in love with & I think she still is. A few months ago I had his phone and saw that he was talking to her again after he said he had stopped. He was talking sexually and flirting with her & some other females. So I broke up with him. Eventually he proved he changed and we got back together. But now it's the same stuff again. She has a whole bf but is talking to him and asking to see him😒 this bothers me so much. But I can't bring it up bc he doesn't know Ik his ig pw and that they've been talking. H E L P