How to stop a cheating husband?

I have been married for 12 years. I am 31 years old. My husband has cheated on me 5years ago, I caught him. I have since forgiven him. Now I find out that he is looking for a fling online! He created a profile to meet other females. I don’t know what to do. I consider myself a good wife, I try to take care of all his needs. We also have a 10 year old son together. Please help

Jyrki