Separation with my wife/Help with the Model/T line

My wife and I have decided to separate after 12 years of marriage.
We have spent lots of time talking and discussing our plan. We have decided to keep our house for now for several reasons. We have decided to start a couple’s therapy to help us navigate through this. And even though we’re doing all the intellectual work to make things as smooth as possible for both of us and for our son, I feel so so so scared that things will change. I know that the decisions has already been made, but my brain tells me to stop and reevaluate it.

My model looks like this:
C separation with my wife
T What if I made a mistake when I decided to separate?
F I’m scared and lost and confused and terrified
A Read books on divorce, talk to my therapist, do coaching and self coaching, etc
R I buffer

I struggle with IM, especially T line. I am completely stuck and can’t find a different thought.

I know that I wanted to separate for so many years. But I consciously chose to commit myself to my wife and our relationship. I did the work on my part and now I’m confident that I need to change my life for the sake of my sanity. How do I change my T line so that my new thought would serve me? Thank you!