Why is my ex boyfriend doing this?

My ex boyfriend and I been together for 3 and 1/2 years.He was the one who wanted to ended it and even when I said we can make it work. He said he didn't want any type of relationship with me. I still tried to make something happen but nothing worked. I got over him and then he randomly texts me wanting to go back. He said he changed and wanted to prove it me. Since we don't live that close I told him to visit me. He was up for it....To make the story short and simple. I guess he didn't want to wait that long. So he told me F this i'm done and all these messed stuff. That showed me that he is still the same guy he was when we were together.

Anyways that day that he told me all these stuff he said he was going try and catch up with his best lady friend and go out with her and treat her better than he did to me.I was like ooh ok, good luck with that. Now he randomly text me in the middle of the night saying he can't sleep. ME being a considerate person that I am.I asked him why he couldn't sleep and he always bring up his bestfriend and how he loves her soo much and going to treat her so much better than he did with me

Please answer this question:

Why does he keep bring up his bestfriend to make me jealous?

If he wanted to be with me, why didn't he wait?

What should I do?