I agree that you are not responsible for her actions or rather, reactions to your breaking up...no more than she is for yours. As adults we make choices (some not so thought out) but still ours.

I'm glad to see you found a new way to show your anger, as I would much rather you take it out on the phone than on you. Now that you have identified this, why not take it another step and work on why you feel you need to be angry, and how you can lessen that need. Take care.