I'm sorry for the loss you've suffered and the grief all the children are going through.
I guess suicide could be considered selfish. I don't though. I think that for someone to commit suicide they must be in such an unfathomable, dark, hole. I can't imagine facing the day with no hope so that I didn't want to go on living and seeing those I love. It's a terrible thing.
They don't leave like that because they are only thinking of themselves.
A boy my son went to school with committed suicide. My son was very subdued and thoughtful as he thought about those last moments he saw him at the end of the school day and how the boy had said goodbye to him...not something he normally did.