Kristin,
I can very much identify with not wanting to transition of even admit to be thinking of it as anything other than a fantasy because of being comfortable in my male persona. I also identified with elements in many other parts of your post.
For me, this came to a head about this time last year. When I got home from the ER, I realised that I couldn't continue to convince myself that all the trans stuff in my head was "just fantasy".
I started with therapy. I felt certain that there was no way I could escape going on HRT, but I wanted to see if I could find a way. So, even after both my wife & my therapist started suggesting I try HRT in early March, I held off on going for it until May. The anti-androgen I started on in May provided near instant relief from the involuntary erections (think 14-year-old hyperactive male libido for 30 years without a break). Once I started taking estrogen in June, the obsession & compulsion left me within 2-3 days. The emotional changes from that have been wonderful (especially from my wife's viewpoint).
I have great difficulty letting go of things. I still have many of my school & college notes & homework books from 20-30 years ago. Transition involves letting go of a very large portion of my life. I have been completely emotionally unprepared to take this on, but I reached a point where I couldn't see any way of keeping going without at least taking HRT.
Because of the conflict between needing to do something to contain the dysphoria and being terrified to let go of anything, I have found myself more suicidal this past year than at any other point in my life. The weekly therapist sessions have been necessary. Even more essential have been the many, many conversations I have had with others who are trans & with cis friends to whom I have come out.
It has been a long year. I have become more willing to let go of at least some of the physical & emotional baggage that has been holding me down for years (decades, even). I am becoming more OK with becoming Tessa, even allowing myself to consider the possibility of being Tessa most of the time.
I have a long way to go. I still present as male all of the time. I rarely wear obviously female attire - & then only at home.
I feel more hopeful about my life this New Year than I have for several years. I attribute this entirely to finding the courage to accept that I needed to stop pretending the desires to be female were "just fantasies" and going to see a therapist who could guide me through the mess in my head. Everything else has stemmed from there.
Good luck! .... If you are anywhere like the place I was at a year ago, you're going to need it.
Tessa.