I have been with my partner for five years now and he has always been a bit of a flirt. It's not normally something that bothered as its usually just harmless. However I have been very low for a while now and have lost most of my sex drive. I have found out that he has been going for drinks with a lady that works in a shop a few doors down from his workplace. I have pulled him up on the fact that he had not told me about it and he told me they are just friends. Not proud of myself for this but I went on his phone and there are so many messages between them. A lot of them are quite sexual with him saying he want's to take her to bed even though she is getting married soon. Again i had pulled him up on this a while ago and said i wasn't comfortable with the contents of the messaging and wanted him to stop. It's carried on. I don't really know what to do.