Name changed for this, but I wanted to add my experience for those of you still living through this.
My experiences were 20 years ago now. I walked into the bathroom to find my (now ex)husband shaving his legs and was told it was because he wanted to become a woman.
As the whole process unfurled over 9 months before I filed for divorce, he talked about his BDSM fantasies (never shared with me in 12 years and in spite of an extremely poor sex life limited by him), about wanting to be a robot rather than a woman per se, wanting to swing as a couple with other people, he started going to transvestite/transexual groups, staying out all night, buying women's clothing, wanting to have a lesbian relationship with me, self mutilating regularly, saying he was going to commit suicide on a virtually daily basis, and eventually trashing the house which was the tipping point.
He was seen by over a dozen health professionals in this time, one of whom was a psychiatrist who diagnosed him with Skoptic syndrome and agreed to the operation to have his penis removed probably about a year after his "coming out". Although our divorce was underway at that point, I did write with my protestations but was brushed away on the basis of patient confidentiality. It wasn't really very much comfort to receive 1) a letter from my ex less than a year later saying he regretted the operation - and I had pushed him into having it(!), and 2) to find out the psychiatrist had been found guilty of misconduct subsequently.
Those were the worst 9 months of my life. For those of you going through the process, finding it unacceptable but not seeing a way to end your marriage, please reconsider for your own mental health and wellbeing. I was "lucky", we had no children, lived away from our home towns, had no joint friends, and I was relatively young - but I was skint for years as a result of the split and mentally traumatised by the whole experience. It did get better though!
20 years ago, the whole trans culture was much more hidden and I was horrified that I had married a man who I felt had rejected me as a heterosexual woman and had made my entire adult life feel like it was built on a lie. I couldn't tell anybody at first, and have just counted that I have told 15 people in all the years since then.
I see all of the trans threads on Mumsnet and it makes me remember about the influence that the people my ex came into contact with; essentially grooming him with what to say to ensure he obtained the hormone treatment and operation. With hindsight, I'm pretty sure he was an autogynephile. I've never had anything but sympathy for people who have transitioned because they felt trapped in the wrong body, but I was certain that wasn't the case for him.