I'm sorry you are struggling at the moment
Just try and remember that you are loved so much by your OH and kids. They definitely don't think your worthless.
I know everything seems so difficult at the moment, it will get better though. Sometimes I think we need to find the bottom, to then turn the corner and start to make our way back up to feeling better again. But, it is so difficult to remember being well. But, you will get there.
Has your CBT started? Please try and eat properly, it'll make you feel better so you can have enough energy to care for your kids. Let your OH prepare the meals if that helps. Just try and be kind to yourself. I know that's hard when all you can think about is punishing yourself. Try and break that self loathing cycle, but believe me, I know how hard it is, and I certainly don't have the answers.
Sorry for rambling. Please take care of yourself