Pat I am so sorry that you are hurting.
But hey it's ok to cry. And it's especially ok to admit to it here.
Look, there are some things that you can not change. How those kids of yours are behaving belongs to them unfortunately. The only thing you can change now is you and your behaviour and where you go from here.
So (and if I sound direct I apologise) why the hell not date? Or at least look into it. You have a computer, there are some good dating sites, why not just look into it a bit. You have a life, but somewhere it has got buried under all the mothering and then subsequently all the pain, so we gotta help dig you out...
Look into it please....if not dating then what about some friendship sites, mutual interest sites - anything that is about YOU.
What about doing some voluntary work? Go read to a blind person (I work with blind people) or go help some other families with young children, heck you raised 3 of your own. An evening class of somekind...learn a new skill?
I know this all sounds hard, and boy is it easy for me to say, but you are gonna have to re-invent yourself and your life. Also if you do this your kids may just start seeing you in a different light and who knows where that may lead...
...do you think you could do any of this? Even just a tiny step forward in another direction?
These are just my ideas and obviously you know the person you are and what you may or may not be able to do. Maybe you could choose something totally different to do in the New Year - something you've wanted to do, but have never gotten around to it.
I'm really wishing you well,