I think I remember your previous thread OP, you all went on a family holiday after you split?
Like many of us said then, it is great the way you prioritise your kids, and your live for them always shines through.
Of course you want your kids to have a hands on mum, for their sakes and for you to be able to have a break now and then.
However, I think you must now accept that she will not be able to be as involved as she should, so you have to deal with the reality of what is happening rather than keep supporting her in order for her to be what you think she should be.
You are a single dad who does more than his fair share. You do a great job. It's hard, it's frustrating to be put in the situation you're in, with a co-parent who doesn't pull their weight, I know that only too well because I've been doing far more parenting, hell, all the parenting, for the past six years. And there are loads of other parents in exactly the same boat. But it is what it is. My kids dad is self absorbed and disengaged and I am constantly amazed at his indifference towards his kids.
But I accept it, roll my sleeves up and get on with it. You must stop trying to change her, and crucially, stop investing so much time and effort in supporting her. She's weak, she sees you as her rock, she needs to stop this, but she won't, so you have to make the change so she stands on her own two feet.
I think I said it on your old thread, but it's worth repeating: You can't fix her.
You can accept that for now your life is dominated by being a great dad. That will change as the kids grow up. You need to garner support from friends, relatives and build a new life for you.
She will always be their mum, but it's up to her to sort herself out and realise that she has to step up. In the meantime let her see that you can cope, you are moving on, but you will no longer enable her to make a mess of things.
Ultimately, if you always pick up the pieces, she'll never learn how to pick them up herself.
And block her on FB. Keep contact about the kids, nothing else. Set some boundaries, currently they're way too blurred