Don't know about FB hurting self-esteem or not, but it can make you feel depressed at times. There was a couple of months about an year ago when I stopped checking my FB altogether, I was going through a low phase and the whole world seemed to be having fun and enjoying themselves and leading wonderful lives. It depressed me no end. But then, eventually I broke out of my shell and as things brightened in my personal life, the depression also went away by itself.