Big hug Kate - and take a deep breath. I know what you are going through. Ever since I told my wife, life has not been the same, only worse. The lid probably cannot be put back on the proverbial box because if you tell her now it was all a mistake, you're not transgender, she'll have to live in denial you ever said it, and it will forever tug at her mind.
The questions you have to ask yourself are "What if you don't transition?" How old are you? Is transition reasonable? Are you ready to lose your wife? Any kids? If you don't transition, can you live with the ever-gnawing regret and thoughts of what could have been? Do you want to be 60 like me and living everyday in pain and anguish, though some days are not as bad as others.
I don't want to push you one way or the other. Ending a marriage and life together is the hardest thing you'll have to do. What will your family say? Only you can ultimately decide if the costs are worth it. You will have accusations thrown at you about how selfish you are. Yes, self-preservation is about selfishness. You have have to live with the consequences, good or bad.
You've got a lot to explore with your therapist and I hope your wife will let you go back.
Big Hugs
Traci