Why are some guys so mean to their ex's!?

Its cool that we've already ended things (although on a bad note). I blocked him off IM and facebook. He then started to go on a mean spree. He commented harsh things on my site, and I know it's childish but I fired back at him and we started a virtual war. And then after that incident, he left me alone for awhile.

but thats not the end, after a few months he texted me something along the lines of "hey lets not be petty, maybe we still can be friends?" and I thought "hmm ok why not". And started talking online again. It was cool for awhile, until he started to verbally abuse me and calling me names, making me feel so...unworthy of anyone else. So i blocked and deleted him off IM again.

and this time, since he has no other way of contacting me, except of course by email and phone, he actually took time and effort to email me a whole chunk of hatred. It was hard for me to read, because it was very hurting. ):

I'm not sure whether he already has a girlfriend, neither do I care, but why does he have to be so mean to me. I was okay with being friends but now, I want him to disappear for good.

help. ):