Married Men

I wanted to get a married women's opinion on this. I have been sleeping with a man for about 5 months. He would talk to me about getting married and how he really wanted to settle down etc. But this week, I found out that he is married and had a newborn baby that was born around the time we met. I confronted him about it and he just blocked me on social media and text messages. I found him and his wife on Instagram but he blocked me from her account too. I did a search on his phone number and obviously his address came up. It's maybe 30 minutes away from me. So I guess my question is, if you were his wife would you want to know? I've been going back and forth in my head about sending her a letter in the mail. But is it worth it break up or affect a family like that? I'm 18 and he's almost 30 so I guess i should have assumed something was wrong. I'm just not sure if I'd be willing to deal with the repercussions of telling her. Any suggestions?