I don't have experience in this type of situation, but I don't have to have any to be able to realize that asking your wife to become a lesbian for you is tough , and excuse my word, but it is very much selfish.
You should absolutely transition and she should respect you for it, but I am sure she also married a man and everything that it entailed. She very much has the right to change her mind over this, just like you have the right to transition because you need it.
if she stays with you then amazing but expecting her to stay, that's a little much. Let me just put it this way. If you were a man and not a trans woman, happy in your marriage, and your wife came home and said. I need to transition to being a man, had Testosterone injections and phalloplasty. I know for a fact many of you would have said ok let's be friends but I can't do this. And would have moved on to be with a woman instead of trying to become a Gay man, which isn't something that can be done at will.