When I felt like this, unable to chose between staying and leaving, I opted to take an 'open-ended break' from T1 and see another T in the meantime. Two months after taking the break. I arranged a final 'goodbye session' with T1 and T2 became my permanent therapist.
Those two months gave me some valuable thinking time, as well as a chance to see how I would be with another therapist. It took me the whole two months to decide, and I think that time was vital.