Why?

Why can't I ever say I'm sorry when I'm angry? It's like I want to, but something is broken in me and the words won't come out. I go to say I'm sorry, and all that comes is another insult or snide remark. Ugh, he's so good to me but I can't even bring myself to tell him. When we fight, all I can do is add to it. I hate it. What's wrong with me??