Hello Joanmarie
God bless you this day. Welcome to Christianity Oasis.
It sounds like you have some really good friends that have concerns -- probably concerns you, yourself, would have for one of those friends in the same situation.
It is difficult to shake the "bad boy" image, but if he truly is a changed guy, it will come through ...in time. Take time to get to know him, and for his true colors to surface. Perhaps your first meeting outside of work could be in a group situation in which your friends are present also?
Pray about it.
God bless and keep you,
Mack