Happy - did you keep waking at 3am when you were still with him? I bet you did; worrying, panicking, stressing, cutting...
It's no different now, just without Him. He is no longer a source of your worry, so you are stressing about other stuff - you can do it. No reason why you can't, you are a strong, capable woman, a mother.
What is it that you can't do? Bring it into the light - let's look at it. What is it?
Don't give up on them. They will be lost, devastated, without you! Even if they get taken in by someone nice and kind, or even their aunt, she is not you!
Can you imagine your poor children growing up without a loving mother?
How much harm you would be doing them in their childhood?
Please stop suggesting your dc will be better off without you. IT'S NOT TRUE.
Please keep posting.