"Then tell yourself to not say anything right then and do something else instead. Like if you are on the phone just say "I have to go now, bye" and hang up. If you are with your gf walk out of the room if you are tempted to say something you'll regret. You will then break the pattern as you keep doing it more and more (it will become a new way of reacting). "

I see what you mean here I think. You are suggesting that my name calling is learned behaviour and I have to unlearn it, by replacing it with another mode of behaviour that is more appropriate. Would that be what you mean?

I dont want to give the impression that I am always angry because that is not true. However, when my fuse has burnt down so to speak, I retaliate in the way I have described. At the time it feels like I want to hurt her without hitting her, because that is not allowed.

I am at a loss to understand how assertivness can help me. Perhaps that is because I do not understand the concept of assertivness as well as I thought. I do understand that to be assertive means to insist on the recognition of ones self. As opposed to aggression, which is to insist on the implementation of ones ideas by another against their will.
Thank you. I will check it out