Most Helpful Guy
Frankly, he's emotionally immature. He was happy when he was "winning" (i. e., when HE was the one in control of the post-breakup situation, when you were still chasing him and giving him attention, and were clearly still wanting to be with him), but once you stopped chasing him, he realized that you could be happy without him, and then he was no longer "winning." He had to face his real feelings - he might be okay with being broken up with you, but he's clearly not okay with being ALONE and "unwanted."
So, he's trying to get you back "on the hook" with him, so that he can bolster his self-esteem and feel like he's still wanted by someone, even if he doesn't plan to get back together with you. It's his way of avoiding the pain of the breakup.
YOUR job is to make a clean break from him. That means NO communication. Sure, you can send him a final email/text telling him that it's in both your best interest not to keep in touch, so that you can both move on, but after that, sever all ties with him and move on.
And let this be a lesson: while you can absolutely remain CIVIL with an ex, in almost all cases, you CANNOT be *friends* with an ex. It just doesn't work, and you should always assume it won't. Yes, there is a rare exception, but in most cases, you won't be the exception. Learn to accept that when you break up with someone, your WHOLE relationship with them is OVER, forever, because that's the reality in the vast majority of cases (unless you have kids together or something).