If I had to pick the most important thing I learned in therapy (and there are a lot of them!), this would be it.
It's not about trusting others, it's about trusting yourself. This is, I believe the single most important shift in thinking for me since I have been in recovery.
It doesn't matter what another person does, it matters what I do. If I am with someone untrustworthy, I need to be able to trust myself to do what's best for me. There were lots of other issues that needed my attention before I could come to the place of trusting myself. For example, I had to learn to overcome my fear of abandonment in order to stop myself from clinging to a relationship that was unhealthy. I had to overcome the committee in my head that told me I was a bad person if I didn't give people "another chance" after they had repeatedly hurt me. And I had to learn that no decision is forever. If I make a mistake, I can learn from it and either right it or do better next time. I don't have to be held hostage by my fear of making mistakes.
Slowly, I'm getting to the point where I do trust myself. And my therapist was right, trusting someone else is really a lot less important now.
L