((((((((((((somebodysomeday))))))))))))))))))
I'm sorry you're hurting so much right now.

If you're in a crisis, please talk to someone IRL but I'll try to help you now if I can, even if it's just saying ... I do understand a lot of the feelings you've expressed here. Each one of them isn't necessarily the most positive, but they aren't bad.
Depression tells us lies. It hurts us, and it can hurt those around us. But it isn't your fault, you're not deliberately going out of your way to hurt anyone... it just happens like that. Some people won't understand, and some people just can't.
I don't think you're a horrible friend, any more that I think you're a horrible person. You aren't, from what I've seen here you're a good hearted individual.
I'm glad you've got good friends who are willing to help, that's the mark of a true friend... the kind of person who you're not always the nicest to, but that they stick around.
You are not a failure, and you are not horrible... sometimes we get so caught up in the lies we're told, and in our cognitive distortions that we can't see the truth.
Who dumped you and who hates you? Unless they have a really good reason for doing so - that's THEIR issues, not yours. What other people do (good or bad) doesn't make you good or bad. It's like looking through a lens at someone else... our views are distorted more than the person who is actually living the life we're observing. (Hope that makes sense).
You do not deserve to be hurt, nobody does. Getting hurt happens, and it isn't fun but you really don't deserve it.
Depression is hard to beat when we're having a rough time.... I hope the clouds clear up soon and you're feeling better.
I don't remember if you've ever said you've got a therapist or are on meds... but if you aren't, might I suggest finding someone to talk to? That can sometimes make all the difference in the world.