Rebound

So u think he’s in a rebound relationship. Weeks after we broke up he was already seeing someone and having sex with someone. At this time I didn’t know. So we were still having sex to. That has been 9 months since and a few days ago we officially cut it off no sex no nothing. But he’s still talking to his rebound. Is that his rebound or no. I felt like if he really liked or loved the girl he would’ve stopped having sex with me. The only reasons why we cut it off because I would let my emotions get the best of me. And I didn’t know he was sleeping with someone else she messaged me. She knew about me because he would tell her all our problems. We have a son together so I figured we were working stuff out. We still went on dates and everything !! But apparently this girl has meet his family and he has meet hers so idk. She took him to Vegas buys him clothes and shoes ect. She’s 28 & he’s 23/ and it’s his coworker. After we officially cut everything off we don’t even text each other not even about our son. But he will still talk to her a such and says he wants nothing from me.