I can relate with you as there are many times where I have the exact same feelings. I never had many friends to start off with, and as time has gone on I've drifted from the "friends" I've made. I put that word in quotes because I don't even feel like they were truly my friends. I've learned to accept that fact. As for Facebook the same can apply on there. I'll post something on FB and most times it'll get no likes or comments which is kind of deflating but not surprising for me; other times it'll get a few likes or a couple comments and while it makes me feel a bit happier, I have to wonder if they truly care about what I posted - if that makes sense.

You're not alone in this feeling and I'm sorry you've had to experience these types of emotions.