I think it's quite ignorant to say it's a selfish act, people who are saying that have clearly never seriously been in that mind frame and therefore don't really know what they are talking about. I am not supporting suicide in anyway, I think it's a wrong choice to make, but if you really are that down, if life really is that unbearable, and especially if your depression is rubbing off on loved ones and creating bad atmospheres and situations, then I can understand, again, I'm not supporting or agreeing with it, I'm saying I understand.
As a person who has felt a slight sting of depression, I've been really REALLY unlucky, and it felt like life was telling me I'm supposed to stay at the bottom, and let me tell you, them feelings suck! My ex gf suffered from depression as a condition, it was a chemical imbalance in her brain that caused it or something like that, there would be days when she would cry and cry all day for absolutely no reason, she wouldn't even know why, she was just so sad and depressed, at times I would catch her cutting herself, and she didn't even have a physical reason to be doing this.
I can see how others perceive it as selfish, but I honestly think you're wrong, but that's just my opinion, as someone has kind of been there, you're thoughts can be, it would be selfish of my family to want me around when all I want to do is die.
I'll end with suicide is the wrong choice to make, but it certainly isn't selfish.