Hi Sad and Welcome to NT
1st off, don't ever say your 3 children would be better off with out you. That is furthest from the truth.
I have 3 wonderful sons myself. They have seen me during depressed times,crying, laughing whatever but they love me! and I know not only do your kids need you but I'm sure they love you very much.
I am sorry you are feeling so down! There are many wonderful people here who are really good listeners. If you want to pm me please feel free!
Take care of yourself. I hope you feel better soon