I'm sorry you're having such a hard time. Ruptures are never easy.

I'm having trust issues with L right now, too. What helped for me is when J (her colleague) asked me what I would tell J to do if she was in the same situation as me. I am able to hold L in mind, so I knew logically that the right thing to do was to communicate with L. And I did. I called up L, left her a voicemail telling her why I wanted to push her away. We talked on the phone the next morning. It helped and it stirred up other feelings. So I emailed L and told her. Her response to my email again helped, but still the feelings persisted. So I asked for another phone call. We just hung up about 5mins ago. I cried, she cried. There were reassurances, and yet again the feelings persist. I have a double session with her tomorrow.

For me, the right thing to do was to communicate with L. In DBT, I thinks it's called opposite reaction. Basically, you do opposite of what you want to do. You know what's healthy and what's not. You know what's right for you and what's not.

Here's a question: what would it be like if you did leave your T? How would you feel? Better? Worse? What if talking to her about everything could strengthen your relationship with her? Rupture/repair is healing and it does strengthen relationships (I find at least).

How long have you been with this T? I have 4 years of building a foundation with L that really helps me during these times.

I know you said you don't want to tell her. I would suggest telling her. What do you have to lose if you're going to leave? Maybe write her instead of verbalizing it? Tell her everything. Don't hold back. If she's a good T, she can hold your hurt and anger. Like my situation, she might not be able to fix what happened (her trying to force you talking about the person), AND there still might be healing to be done in it all.

Whatever you decide, please stay safe!