As you should be! I think it's important when we hurt ppl, even accidentally, to not only apologize, but to explain why you said or did them. At the very least it should bring respect back, and help open dialogue for working it out, becoming friends again, or even just closure. Keep double checking when you are about to do something that may make things worse, it's not easy but it's how you'll break from those behaviors even a bit. Certainly better than not working to control them. *hugs*
And fwiw, break ups are hard. They hurt everyone. Have compassion both for her and yourself.