Search Results: he might make out with another girl

I already asked questions about him. He is an ex friends with benefits, it's been almost 9 months we didn't see each others. I developed huge feelings for him meanwhile.
Since our "breakup", he's constantly bragging about girls he is dating, even if he finally doesn't like them and that it doesn't last more than 3 weeks.

Recently he recontacted me to tell he missed me and that things were better with me. He also told me he was lost and didn't know what he wanted. Finally, out of the blue, two days ago, he said that he "wanted me" (desired) but had no feelings for me, just wanting sex. Even if his actions for these last months seem to show the opposite. And every time I say "No" to him, it's like he makes me pay for it.

Yesterday he just texted me to say that he had sex with a girl and that he wanted to let me know it because he prefers to be honest. I told him he had no reason to tell me this, given that we are not a couple and added that he might be kinda desperate to come back with a girl whom "sex was bad" (he told me it two days before). He just replied me in an very upset way.

Don't tell me to move on and that he's a jerk, I already know that.
I just want to understand what's the point of telling me that if so-called he doesn't care of me? Why to try to make me jealous?