I know how you feel. I sort of let go of most of my friends because I didn't really want to be a burden to them. I'm always depressed, and all I seem to know how to talk about is how much I hate this world, or how upset I am at x y and z. To be fair, I'm pretty positive my friends were pretty tired of hearing it, so I likely did them a favour.
It probably wasn't the best decision, though. Isolation makes this sort of thing much worse... and so does pretending to be happy when you're not, often enough. I would say that you should feel free to be more honest about your feelings around friends, and if they care about you then they will show it.
If you find out that they don't really care, then ... well, they probably aren't great friends. It's unlikely that you have no one that cares about you, though.
Even if you are out of people who care about you, then at least you will have yourself. I don't know how others view themselves, but having a sort of duality in my own person... I think of myself almost as two people, spiritually, and when I'm depressed, it helps to remember that I'm here to take care of myself, and that I'll always care about myself, and be there for myself, and remember to love myself. I treat my 'second half' as a caring mother figure, or a best friend figure.
Talking to oneself can do a world of good when one remembers to say genuinely nice things. It's about finding strength from within, and it's important to know how to do... because, in the end, people can only rely on themselves.
Until now, I had forgotten about these things... so I have to thank you for the reminder.
