I don't think I've ever been used by friends, but plenty have abandoned me. I grew up in a military town, so every year at least one friend with parents in the military would move, never to be heard from again. The group of friends I had at the beginning of my freshmen year of college also stopped hanging out with me.

But the big one was when my best friend from high school made plans with me to hang out 4 times and didn't show up to any of them and didn't give a reason as to why she didn't show. Which sucks because it's really hard to think back on the good times without it being painful in some way.

Right now I don't have any friends, which I think is a good thing for now. I have big trust issues because of the above situations and being alone is giving me time to trust myself to trust others again.