Honestly Emily, this is all so familiar it's like I'm reading my own diary.
I don't know if STBXH would be out, if he hadn't backed himself so far into a corner with his threats and shitty behaviour, that really he had no choice.
He only came "out" when I took him to a private doctor then paid (through insurance) for the Priory. I took him to the doctor because he was at the height of a pink fog binge, making horrible demands of me, and being aggressive. He was threatening suicide if I didn't "get with the programme". I was forcing him to kill himself with my non compliance, of not accepting his sexy thoughts as truth.
I think if he hadn't gone to the Priory we would have continue to binge/purge cycle, with each of us getting more desperately unwell.
Lucky for STBXH, coming out has absolved him of all responsibility for his crappy behaviour, lying and making me his beard for 20 years "understandable", he's so brave etc.
Prep hard, because once out public understanding and sympathy (for you) is in short supply. If you are further broken by him, it'll be shit.
You need to know that it is him, not you. That you are the expert when it comes to how you experienced your marriage and his sexuality. You need to develop a hide to protect you from the dimwits who read a few guardian articles, don't know the difference between transgender/sexual, but still assume they have a greater understanding of your marriage than you.
Sorry mate.
Saying all that, it is so much better out than in. Oh my goodness, so much better.