I can see why it's difficult for you to trust yourself. But I still don't feel that it's your own fault hon.
As much as I hate saying this sometimes, it's just because that people sometimes just change for worse. We hate to see it, but it happens.
They change, and sometimes they become less trustworthy, and that in itself has nothing to do with you.
And just to clear something from your recent post out, we're not using you. People like Slush, Mav and I don't use you for anything. We all enjoy your company because to us, you've been an amazing and trustworthy person for us.