Oh Sweetheart I don't want you to cry. I am so sorry. Although sometimes crying can help get it out.
It was 4 years ago...so that's a good thing. But your hurt is right now. Text messaging really can't convey your hurt. It's too swift and instant. You need to sit down and type up a letter or handwrite it.
You have an awful lot of hurt inside you that has to heal. Getting his understanding of how this made you feel and a sincere apology will help the healing begin.
Flower it was 4 years ago and thankfully nothing came of it and his being honest with you
are very positive points.
You want to get the hurt out, be heard and understood, but you don't want to hang on to it and carry it with the both of you forever. That's why it is important to take care of it and then leave it behind you.
Your sad heart is understandable but work with your husband in helping to put this behind you both.
It probably was very meaningless to him and more then likely driven by the alchol consumption of New Year's Eve (assuming he was drinking).
You hang in there girl...this will be okay

. That's a promise!!