I'm not sure this is of any help, feel free to ignore me or tell me off if it bothers you.

I've repeatedly had instances where people in my life left. Not all for the same reasons I'm sure. Some died. Some were teenagers who changed their minds of who to be friends with. Some were people I exhausted mentally or overwhelmed. And with some the contact just stopped after a while, whether it was because of somebody not answering or nobody reaching out to the other one anymore.

Some of these things hurt more, some less. People from primary school that got lost somewhere along the way? I probably barely even remember their names. People (and pets) who died? I grieved for a while and at some point it got better. If I think back of those people and animals, I'm sad they're not here anymore. But I have nice memories of them and still love them and keep them in my heart.
People who I thought were my friends who suddenly ran away from me and started ganging up on me? Those experiences made me scared of people. They made me hide in my room and cry for months or even years.

But all these experiences had one thing in common: it got better with time. I'm pretty sure I missed my best buddy in kindergarten the first time we didn't hang out as usual, and was devastated by most other losses. But by just keeping on, it got better.

I have new friends now. I'm planning on getting a new pet. And at some point I've realized that the people who truly just hurt me did not deserve a place in my life anyways and I found better people instead.

I can't tell you what exactly your solution will be. I've never managed to forget any of my memories. Not even the most painful ones. But the pain got a lot less. With some experiences it never went away completely, but with most it got to a level where I could function normally and would think back of them once in a blue moon. I hope that you can somehow manage to get to a similar point, where maybe you realize that some of the things you went through with your T were horrible, but other things were nice. And where instead of thinking back of therapy as something that brought pain you can think back of both the joy and the pain.