Ex wanna come back to me and yet choose her (rebound)

So my ex came back and reached out after 2 weeks asking if I have someone new, I said no. Then he said he wanna try again. Then I said didn't you have a new one? He then said that he got too obsessed and attached with her and he hates that to the point he almost killed himself. Then he said if he say smth I should do it. Then he told me that he left me bcs he got boring that I never said freaky stuff back at him. We're at ldr. I told him he should have told me that. Then next day, I told him this "If you ever decide that you truly want to be with me again, I would need you to fully choose me and not be involved with someone else.That would also mean unfollowing her and ending that connection so there’s no pain and confusion, because I wouldn’t want you to still have lingering feelings for someone else while being with me." Then he said he needed time to think about it then I gave him that. Next day again he unfriended her for an hour I think idk but then friended her back again on every social then unfriended me. So I js know what decision he made...he choose her. I ask him why her? He said it's the way she acts and talks to him and he doesn't know why. I got hurt ofc.

I js know he's mental health is a mess bcs I saw a user name of him on a game with the same 'cuttingforher'..so I js know it's Abt her, I broke down bcs he's not like this before he told me he changed after everything. I got so worried at him that I told him to js leave her bcs he's having suicidal thoughts. Then he said he was happy till he met her...and then told me that if I knew he acts like this before I would leave him, I told him I wouldn't and he should have told me before... Then he said goodbye to me and said that if he doesn't talk to me anymore js know that he's gone...I was already healing for a week and then he reached out only to hurt me again and leave me...