Something similar happened to me with my first wife … I read an email meant for her that was quite descriptive, not to mention x rated, and it left me pretty devastated. I was in a very dark place after that. But now, many years later, I’m very happily married to a partner who is perfect for me in every way. My advice to everyone who goes through this is hang in there, it hurts like hell but things will get better and one day you’ll look back and realize it was better you found out and got out when you did.