My fiancé and I have been together for 3 years and we are getting married at the end of the year. Last night my friend told me that they had been talking harmlessly on Facebook. At first it was fine but then he started saying inappropriate things. He is a very blatant kind of guy and does say some things he shouldn't. She showed me the conversation and it wasn't as bad as it could have been but it was still inappropriate and she felt uncomfortable. I confronted him about it and he admitted he had done the wrong thing and was sorry. He has never given me a reason not to trust him up until now. How do I approach things now?

I'm assuming he has agreed not to chat with your friend anymore. You either trust him or you don't.