Something occurred to me.
You have a lot on your plate. Your DH is leaving all the childcare to you, and not nourishing you in any way. He's not treating you like a person with needs. Your needs are being neglected by both him and you, and at the same time the children need you.
My friend who was suicidal, was at her worst at a time when she was doing a lot of caring for others and had totally lost her sense of self. She honestly believed that everyone would be better off without her, when from the outside it was obvious that the reality was that the people she was caring for needed her very much. But at the same time, she was getting no chance to rest and recharge or do anything for herself.
Her suicidal thinking was her depression talking, and thankfully she got help and those days are long in the past now. Part of her recovery, incidentally, was getting divorced! FWIW, her DH wasn't a bad man, but their relationship didn't suit her at all.
I wonder if it's the pressure of the way you're living that's leading you to this kind of thinking. Does that make any sense?
Would you consider talking to the Samaritans maybe? It's anonymous.