I would only add as a reminder that anything you put on the internet is there, forever. You might want to watch putting admissions to affairs here as it will hang over your head, forever. No better proof than ones own admission.
You need to relay to your husband that you do not feel it is fair that after 10 years, you should still be expected to pay for something that happened that long ago and you will no longer put up with it. The next time he does this walk away, go to a different room, or for a drive, to the mall, whatever but make yourself scarce. After he realizes that you refuse to participate in his insecurities and that every time he broaches this subject you are gone, he will soon stop. It may take a few times or even 9 or ten, but be patient and make sure you do not respond in any way other than to disappear from the conversation. If he ceases to get rewards of your reactions, it will stop.
Well I don't know what to tell you. I guess if you play you pay. Although, I don't think it's fair that he constantly throws things in your face, because if he chose to forgive you and stay with you, he can't mentally torment you the rest of your lives together. But no one can change how he feels. Perhaps you can recommend counseling for you both. He doesn't seem to have an outlet to express his true feelings other than resorting to verbally assaulting you with it on all occasions. You can't change him, he has to want to let it go. So my only advice would be for him to seek some counseling. Other than that, if you can't take it, you may just have to leave him.
So you cheated, and he ever found about it (to your knowledge) and then you had some flirty thing 10 years ago that he did find out about.
Girl, why can't you behave?
This happened over 10 years ago?? I think your husband really needs to let this go, and that it signifies some deeper issues that after all this time, he still dwells on this so much. Ten years and 2 kids later, I think it should be an unpleasant but vague memory for him. Instead he makes sure to keep it right at the surface of your life by constantly throwing it up in your face. I think he is a very angry man. After someone is betrayed, there is a period of time in which many things bring involuntary pain and rage- certain songs, words, etc. That is a very painful stage- I've been through it in a past relationship. But then, as time goes on and happier memories are built, those automatic surges of bad feelings begin to lessen. They become less intense, less frequent, and faith and trust are rebuilt slowly in the relationship. Eventually, those same words/songs/etc that were once such painful triggers become meaningless. Positive experiences and feelings have layered over those triggers until they are simply no more. But in order for this to happen, one must not purposefully recall the betrayal. In fact, after the initial turmoil following the cheating, an effort must be made to redirect the mind when it turns to those negative thoughts. It sounds like you and your husband have built plenty of wonderful memories together- including bringing two lives into the world! I'm not sure how old your kids are, but your husband's behavior is not good for them. If they actually hear and understand what he is talking about, that could severely damage their image of you, and that's not fair because all this happened before you became a mom.
I think you should sit down with your husband and explain that you love him and only him, that you deeply regret your past mistakes and would love to undo them, but that it has been a very long time and you have proven your love and fidelity to him and need for him to forgive you, and suggest counseling for both of you. It will help you learn to stand up for yourself and refuse to be drawn into his resentment, and give him tools to overcome this thought process that is most likely torturing him as well as you. Unless youir husband is a cruel man intent on hurting you, this must be awful for him too. Initially I just thought of how awful he's acting to you, but then I started trying to think of how he feels if he doesn't think he can control this. Imagine being trapped in your own mind and constantly assaulted with these thoughts and images. It sounds as if that's what he is going through. Of course, this is giving him the benefit of the doubt and assuming he's a nice guy and really wants to get past this.
I really hope you can work this out- best of luck :)
See a therapist together.