Megan, your wife screaming, throwing things, and manipulating you and herself away from therapists—those are all forms of abuse.
You really need to stop living in ugly compromise, both with her and with yourself, and get away from her even if you do not transition. That is a reality you need to come to terms with as you fully realize who you truly are.
My wife is not abusive, but she always put her family (who are in a foreign country) first. Everything was always about helping them, sending them goods and money. It was clear a few years in to the marriage that she would always love them more than me, put them above me, and that I was pretty much a grunt or foot soldier in the effort to help them prosper.
I'm not complaining; they are good people and they care about me. But I am making the point that I eventually realized that the only person in the world who would ever love me first and best was me. In the end, transitioning improved our relationship, my business, and made me a better me.
You need to really take care of yourself and not be passive about it.
My suggestion is, rather than just splitting, lawyer up first. See a lawyer, pay a few bucks for a consult, and find out what is really likely to happen in a divorce. Then, when you do confront her, you can do so with confidence and if she makes trouble you have some backup.
Hugs, Carly