Cruel keeping someone alive when they’d rather be dead?

I feel as if im trapped in a body, that I can’t escape. I feel like I’m a failure for an unsuccessful suicide attempt. I always look back on that day and wish It worked, I cross roads without fully looking in hope ill get hit. I’m sick of putting on a happy front when I’m a mess inside. Mental illness is such cruel thing to happen to someone, and even though I hate it somehow I delve in it and some part of me wants to suffer, and I can’t understand why. I managed to keep on top of my illness for a steady 7 months and now I feel myself going back into that dark place. I don’t even know what to do anymore. I can’t talk to my family because they all have mild asbergers and don’t understand feelings and emotions that well I have up with friends because i can’t let them know how much I hurt because they don’t understand and won’t actually care, I don’t want to tell councillors because they don’t care it’s just their job I want someone to really care about me and my head rather than pretend to because if I top myself they will look like a ‘bad mate’ isn’t it more cruel keeping someone alive and living hell rather than letting them go and not hurt anymore?