My wife is pregnant. What do I do?

but here's the catch. I'm 27 and I had a vasectomy done 7 years ago because I decided I never wanted to have kids and that if I had gotten married before I had one done,then the wife has to be aware of it and agree to it. I got married three years ago and I never brought it up and she never brought up the idea of kids when we dated. She had been wanting to try to have children for the last two years and I didnt have the heart to tell her that I had the procedure done. I dont want it reversed becasue I dont want kids. Now she's pregnant,and i know it's not mine.What do I do?