Keep trying for the sake of the kids. They will no doubt be getting a load of lies from her about the both of you, but actions speak louder than words and they will soon realise that neither of you fit the lies she's been spinning.
Children with a mother like this usually turn against her as she is a destructive force and they remember how nice and calm it was when they were with dad.
For now all you can do is keep repeating yourselves like robots, over and over. Don't change the message. Draw up a system of contact and stick to it religiously so that she can never accuse you of moving the goalposts. If you are meant to have them every other weekend then keep turning up that weekend, even if she refuses to answer the door, keep turning up, keep reminding her of the rigid plans put in place that she agreed to.
A standard response along the lines of "thank you for your text which we shall store with the rest for future use" should soon shut her up. She knows then that you are saving them and you can potentially use them in court, show them to the kids when they are older, whatever. Don't let your response to her change in any way.
If she does come up to you being friendy, then be friendly and civil back. She was making a public show there, no doubt there were people watching (her friends? the kids?) so don't give her any ammunition, just grit your teeth and smile and suggest that you all run together. Trust me, she will be expecting a knockback from you so if you actually embrace her full on she won't know what to do.
Sometimes you have to beat them down with kindness because there is no response to kindness is there? What can you say? Next time she is nice in public, go a step further, invite her out to lunch. Suggest all the kids have a sleepover together at her house 
, put her on the spot.
But never ever give up trying. My dad never did and I'm so very pleased he didn't.