I know the feeling so well... The nobody would miss me if I were not here thing. Of course it is not true, but it is a very real feeling while it lasts. The good news is, of course, it does not.
You are, very understandably, being a bit harsh on your kids. They ARE kids, they are supposed to be self-oriented and centered on the present: what is important to them is that they are sure of having both of your love. So sure that they do not feel threatened by not having Dad at home. You are analyzing their behavior based on adult norms, not children's. So do not 'blame' them for not appreciating your sacrifice and your care: they will not until they are parents themselves. For them, you exist in this world with the sole purpose of being their Mom. And that is what Moms do. End of story. At their age they do not see the implications of the situation. Or how you feel about it.
And I have good news for you, my dear. When you reach the point in which you do not give a da** about it anymore you've hit bottom. From now on, things can only get better, even if it is in unexpected ways. And the suffering will lose its edge. I promise. Somehow the pain blunts.
I wish I could fast forward you 5 months. Even two weeks. And show you the difference. But I cannot. And I had not discovered DR and the board then, so I did not post. You'll have to take it on faith.
Hold on Jackie. You'll survive.
"You don't throw a whole life away just 'cause it's banged up a little"
Tom Smith in "Seabiscuit"