I told my wife because I knew who I was and I didn't want any secrets. I didn't want to hide anything from her. And I told her within a week of meeting her face to face.
I know most of my desire to crossdress came from when I was a teenager. Seeing women in lingerie excited me and I found pleasure when I felt it against my skin. As I grew older it no longer excites me that way, but I am more relaxed and comfortable when I am dressed.