We had a vicious breakup where he dumped me to "move in" with his ex. Why hasnt he deleted me from his myspace?

Probably because your page is private and he still wants to see what you are up to and what you are doing, maybe if he deletes you he won't have you there on the back burner in case something happens with his girlfriend....it is time for you to take him off he knows that you are still holding on!!