Thank you so much for writing. I’m sure it was painful to think about your problems with the first boyfriend. Although your time with him was not healthy, it was very, very intense. The two of you were in a mutually destructive cycle of self abuse and mutual neediness and reassurance and more self abuse. I’ve found that the intensity of this kind of situation is both terrifying and addictive. It makes sense to me that you are afraid of getting back into such a cycle again.
Before you can trust other people, I think you have some healing to do so you can trust yourself not to get caught up in such a destructive relationship again. If you could do that on your own, you would have done it already. For that reason, I do strongly urge you to see a counselor to help you recover from a traumatizing relationship and to help you start trusting yourself again.
If therapy isn’t available in your city, a place to start is one of the forums here at PsychCentral. People from all over the world give each other advice and important support.
I wish you well.