Looking good while feeling miserable when in front of the kids, was a huge challenge for me as well. And I didnt do good at first. They saw me crying, depressed, fighting with my mom, etc etc... I sleep a lot when sad too, they would watch TV and I would sleep. I know it wasnt the best thing for them, but it WAS the best thing I was capable of under the circumstances...
Take care of yourself, you cant be of any good to your S if you are not OK, you are the priority now. Hugs K