I believe that it's important to understand what's mine and what's not mine. I have a role in everything that's happened in my life, so I try to understand what my part is and whether I have an obligation. We don't have obligations to be or remain friends with anyone. If there is something that you did to wrong your former friends, it's probably good to face up to that at some point, whether or not that means that you become friends again. If you end a friendship with the intention of allowing them to find better friends, perhaps try instead to become a better friend.
One of the great paradoxes I find is that in order to become trusted, it is necessary to trust. I used to think that by keeping secrets, I was demonstrating to everyone how trustworthy I was, but people didn't confide in me. I found out that by sharing about myself, by becoming vulnerable, I opened the door to people sharing and opening up.