Rainbow, maybe it would help if you could see it this way. You do have a real relationship with her as an adult, and you also have a relationship with her that's based on experiences and feelings from your childhood. Those feelings, from the past, are the ones that get stirred up and they tend to intensify and take over, and when that happens you seem to lose sight of the fact that you still have a real relationship with her as an adult.
I think if you can work through this, you will be able to accept the adult relationship you have with her as the one that's real and lasting. But part of working it through requires accepting the fact that the relationship you want with her -- the one that's based on childhood needs and feelings, where you would be getting your needs met by someone whose focus is on you and not on herself -- would not be healthy for either of you.
You will gradually and naturally give up your need to have your T be "the one" if you can accept the real relationship you already have with her, accept the past for what it was, and work toward cultivating relationships with people who are caring and compassionate. It's real important to surround yourself with people who will allow you to be yourself, people who will accept you as you are and don't need you to pretend to be someone you're not just because of their own issues. It will take some work, but when you find some people like that in real life, it will be easier for you to give up the fantasy of your T being "the one."