Nabster. When you feel like that it's very hard to see the bigger picture. You may not want to continue with this life for whatever reason, but believe me, this life is a better place for you being in it.
I say that because your kids love you dearly and their lives are better and happier for you being around. They need you, they depend on you and their mental wellbeing is largely down to you being there for them.
Your dh's life is better for having you around. He has someone to share parenthood with, to laugh with, to talk about memories with. Little things like what your ds said that was funny - he can share that with you and you both understand, you know your children so well that you don't even have to explain anything, just a word sometimes is enough and you are both on the same level. You are his best friend and he loves you.
Then there is your wider family, who have seen you grow and develop. Your friends who have shared secrets with you. All of these people would be left with a huge gaping hole if you were not there.
My dh's cousin killed herself when she was only 21. He was a teenager at the time. She'd tried before. Her mother had died when she was very young, she had 7 brothers and sisters and life just got too much for her. dh was very close to her and even now, years later, her death affects him. It has left a hole in his life. Her father suffered tremendous grief and all her brothers and sisters, to differing degrees, have experience mental health problems directly as a result of losing 2 people very close to them.
My brother tried to kill himself 18 months ago. He was in a very very bad state. He was married with kids too. He would send my sister and I texts along the lines of "say goodbye to everyone for me", it was terrifying. For a while we wondered if he would ever be safe. But with a lot of help he managed. It was a long, hard journey but he's just about getting there now. The only thing that stopped him from taking his own life was the thought of ruining his children's lives.
You are in a deep, dark place right now. It would be impossible for you to get out of there without some help. If you had a severe illness that threatened your life would you not go to hospital? You wouldn't try to treat yourself would you? This is a life-threatening illness you have? Depression is an illness. You need professional help to treat it. You are not just seeking attention. If you staggered into hospital with malaria would they say you were attention-seeking? You have an illness and most medical people would recognise it as a serious one that needs treatment. So do the right thing and accept that help, accept the treatment.
If not for you, then do it for your children.
Best of luck.