I do understand what you mean.
I felt similarly when I was in a crippling depression. That was the first time I really and truly could understand why people choose suicide.
However- if you believe in energy, which I do, if you choose that route, you aren't becoming from suffering, you are just magnifying it and passing it on to the people you love.
That's enough of a 'why' for me to keep going.
Also, I do believe in karma and reincarnation, and I don't want to come back in even worse shape than I am in already. No matter how bad I have it I know that there are people who have it worse.
I'm sorry you are struggling.