I had sex with a married man I had no idea he was married until it was too late..

I was the other woman I feel to gross with myself. I was dating a married man and didn't even know it I met him online and we went to a few dinners and had sex then I wanted to surprise him at work and seen pictures of him and his wife. Broke up with him instantly. Now my question is do I tell his wife I feel like I should but I don't know if it's my place. I found her on Facebook. He doesn't have a Facebook so I didn't know about her but on her page it's all pictures of them.