You sound pretty rational. And I'm sure you and your therapist is right that you're TS. But you still have to make sure you don't focus on that too much and blame it for all your depression. I've seen a lot of people who are depressed for plenty reasons and they have a lot of stuff to deal with in their life, but they decide it's all about their gender issues. And then when they transition and their life isn't magically fixed they freak out. I'm not saying that's you. I'm just saying it's something to keep in mind, because transition makes your life more stressful, not less stressful -- although it's still something most of us decide we have to do. It's just important to try to deal with as many other stresses as you can first to prepare for that big one. And it's definitely a big one. I think the decision to transition is about the only thing I would rank above the decision of who to marry as far as important events in your life. But it should be a wonderful thing, starting your real life.
It's cool that your wife has the clarity to say she can't stay married if you transition. I think a lot of wives have that "love conquers all" optimism then after the transition realize that they're just not lesbians. And a lot of TS women think it's no big deal because they want to maintain the same relationship so what's the problem? And this is something that I don't really hear people talk about, but that's a whole other transition you have to go through if you're a transwoman attracted to women. You have to transition from being seen as a straight guy to being seen as a homosexual woman. And for me that was awfully awkward, because I had prepared in my mind for a long time for the gender transition, but I wasn't prepared to be publicly gay. It's all the little things -- like the looks people give you when they see a grown woman holding another grown woman's hand in public.But maybe that's just me.
Of course, if your wife doesn't want to be married to a woman, she'll eventually figure out that she already is.
If you're not sure about the transition ... well ... I think what finally helped me sort things out was trying to focus on what future I really would be happy with. Not even happy so much as what I could handle. And I just couldn't handle the idea of the next 20 years pretending I was a guy.