Why is he so angry?

I broke up with my boyfriend 2 weeks ago because he cheated on me with one of my friends. We have known each other for a very long time, so of course we're staying in touch. We still remain friends and we talk to each other on myspace. I have tried Yahoo! answers, but the people there are so rude! Anyways, last night I was talking to him on myspace. I told him I had to go (we had been talking for at least an hour). He asked why, so I told him. I had to call my boyfriend Zach cause he had been sick for 3 days, so I wanted to check on him. My ex got so angry saying that Zach should go f*ck himself, and that he'd kill Zach. What is wrong with him? Why did he get so angry? (I wasn't trying to make him jealous, and I didn't say this to make him mad, but he kept asking me why I had to go, so I told him.)

[redneckmom]

Your ex is probably angry because you moved on to a new boyfriend so fast.  

[dove3053]

What do you mean you have been friends for a long time so of course you staying in touch. He cheated on you with your friends.

First of all I wouldn't be talking to him at all.
Second I would take a long look at your life and friends.

Unless of course you think it's ok he cheated on you.

Why don't you get back with him so he can cheat on you with some more of your friends. Don't mean to sound harsh--but what do you use for brains?

Dove

[S_O_S]

Of corse he's going to be angry, Guys are soo weird. I had a boyfriend who Totally took me for granted and what not i ended up breaking up with him but he knew i still liked him so i guess he had me "in check" and he could do anything with girls. But as soon as i got a boyfriend he started wanting to talk and would get mad at me and would call me a **** for kissing my boyfriend. Honestly. I mean come on. So i think certain guys like your exe still want you to like him just so he knows he has you "in check" incase yall got back together he'd know he could cheat again. You knnnow?

[chigirl29]

Why do you even care if he cheated on you?  I wouldn't.

[SeriousSam]

If you stay friends fine.  Don't talk about current relationships though unless you just like getting a rise out of him.  For one reason or another he still has feelings for you.  You both at this point need to not be baiting each other until you both have moved on to new relationships and accepted that you do not have "rights" to each other.

How old are you guys anyway?  High school? Early college?