I think you can get it back. It was there, so you know the potential (sadly, I'm not sure I can say the same - H did some sweet things for me a very long time ago, but could never compete with yours!).
Seems to me the kids changed everything in your sit.. So you need to reclaim as much as you can of what was different then. I know you can't change it all, but you are making a good start, taking the emt training and looking towards working. It will add more balance to your roles - although more stress too, as you won't have as much time for household chores and child care, but maybe this will mean he has to adjust what he does to compensate. And I think he has it in him. I remember you saying early on that he was already then (I don't think he was home yet) starting to help lots more around the house. And he's obviously invested in the kids. That's huge.
Don't quit now LL - think of how far you have come!