Not so much to the degree that you are experiencing, however I worked quite closely with a girl living with someone who transitioned during their relationship.
This was over 10 years ago, the transition of this girl to live her life as a man is complete.
They are very happily married and very open about their transition and those who have met them since the transition would not know, unless told, that they once lived their life as a girl.
I don’t pretend to understand, but it’s obvious they are happy.
Please just hold onto the fact that it is the same person inside, still your dear friend.
I wish you both well 