I made a big mistake

I think that if you honestly KNOW in your heart that the kiss was a mistake and that it WON'T happen again and you sincerely want to work on your marriage then it's best not to tell your husband.

The amount of permanent damage that might be done by telling him is probably not worth it. Telling him could cause him to stop trusting you, make him insecure, etc. and if you are SURE that it was a mistake and won't happen again then I say there's no point in putting him through that just to make yourself feel better.

Now is the time to really take a good look at your marriage and put your all into making things better.

Good luck!!
 
If you love your husband I think you two should sit down and have a good talk, tell him how you feel, first tell him you love him and want to work on things (if that is how you feel). I know I am in the minority here and I hope no one gets mad, I also hate giving advice because you have to do what your gut tells you to, but...I do not think people should lie, I think honesty is really important in a relationship but I don't know how your husband would take an admission to kissing another guy, he might flip...you have to feel it out, make penance somehow so you don't feel guilty. On a side note sometimes the truth makes us feel less guilty but hurts the person we tell the truth to. Good luck and I hope you end up happy whatever your decision is.