Wait, wait…if it is so hard to get him mad, why do the two of you argue so much? From what you’ve described, it sounds like it is the opposite; it sounds more like he gets angry easily and says hurtful things.
You have no control over your husband; the only person you have any control over is YOU- when he is angry and says hurtful things, you do not have to respond. I know it feels like you have to; but when you respond, you are only keeping the arguing going. You can make the choice to not say mean/negative things back. I urge you to just try it a few times. As you said, you know that you’ll be fighting again later, so why not go on and give it a try- just simply do not respond. Instead, make the choice to either leave the room, or say, “This is getting heated fast, lets take some time to cool off and then talk about it.”
I can honestly say that I have never said hurtful things just to make someone else mad. I’ve had some arguments in my life, and I never had to make anything up that was hurtful; if I said it, I meant it- I probably regretted it later, but I either say how I feel at the time or say nothing at all. I’ve learned, as I’ve gotten a little older and more mature, that it isn’t necessary to say hurtful things, it isn’t even necessary to argue. You can refuse to engage in an argument, what is he going to do, argue with himself? I doubt it. As I said, I know it is difficult to break old habits, even ones that are bad for you, but it sounds like you are tired of this cycle and only you can do something to break it. Best wishes!