"I think it would be a huge relief to start over with someone different, and this time hold on harder to the boundaries in my head -- to always, always keep in mind that this other person is not really emotionally invested in me and doesn't actually care about me in real life."

I don't know. I get the feeling you are trying to run away from apparently a very good therapist because you are trying to escape something that I'm not really sure is possible to run away from.