My husband has become close friends with a female work colleague. About 2 years ago he was on his way home from a work night out and sent me a txt meant for her saying he'd rather spend time with her than anyone else. When I asked him about it he passed it off as drunken banter. Since then they are always commenting on each other's facebook. When he was off on paternity leave recently I saw him txt her to say he was missing her. He said it was work banter. I stupidly checked his txt at the wkend and he'd asked her to go to the cinema. There was also a txt asking how the suspension on her car was and she replied fine no thanks to u with a wink. I'm so confused as he's so loving at hone. I explained their friend ship makes me uncomfortable but he says he won't be dictated to who he is friends with. She is married but recently separated. One day they spent 12 hours on facebook to each other. What should I do?