You've explained the problem accurately: overwhelmed. Try and stay on one item, telling yourself that's "all" you have to do. It's the only way I get anything done when overwhelmed.

Some things have to be put on the back burner. Some things will never be done. Try and take as many things off the list as possible... could be they are on their because of some "rule" of life.

I learned that linens don't have to be folded, the dishwasher doesn't have to be emptied of clean before you add dirty and run it again... stuff like that.