Should I tell his wife?

I went on a vacation with some friends last week and met an amazing man. He was romantic and affectionate...said all of the right things. We spent all of our time together and had some wonderful sex. He indicated that he loved everything about spending time with me and that he'd like to see me again. We exchanged phone numbers at the end of our vacation but I have not heard from him. I decided to look him up online and discovered that he is MARRIED. I found his wife's blog and learned quite a bit. They have been married a little over a year, are actively trying to get pregnant and it seems as if she puts her heart and soul into everything about this marriage. Her e-mail address is linked on her blog and my question is...should I e-mail her and tell her that her husband has cheated on her? I am sure I am not the first and will not be the last, but I also know this could bring her much pain. I am on the fence and not sure what to do.