You know.. I think that he is being a tad childish.. Deliberately baiting you..
You say he brings up your infidelity from time to time and it bothers you alot.
I think sometimes it goes deeper than "a mistake" in the other persons mind, perhaps he is thinking, "wasn't I good enough?" in bed, or otherwise but usually it's the "bed" they are thinking about and their self esteme is blown.
I personally think from what I just read, I think this is his "ego" , "mucho" and a way to get over what he "hasn't" gotten over and I agree therefore with the other two posters..
Don't confront her.
But, ask yourself also.. Whilst you have gotten over it, does your husband feel totally and 100% totally, "the man", I don't think he has gotten over it which means he isn't quite believing you won't do it again.
Trust is a hard thing to earn. Fighting to regain other than "I am over it" is another thing to learn.