Bigblue has said what I was thinking too - it will reduce her credibility with the "my marriage is over" line, having a knees up with her cronies and posting it all over FB.
I have to say that is THE most tasteless thing to do - totally spiteful and vindictive and pretty much tells you all you need to know about their collective thought processes.
Disengage, step back. Don't make any further comment on how you feel as they'll take that back to C and L. There is no way to "win" this - the psychopaths are always steps ahead because they have no moral code, no conscience and absolutely no compunction in going that step too far that no normal person would!
So your only option now is to reduce contact as much as possible, without looking like you've thrown your toys out the pram. So - keep cool and civil with them if they talk to you, don't turn your back or ignore them, but don't invite contact either. Don't comment on WhatsApp to start a conversation - reply briefly and to the point, with no emotion. I don't know whether or not they will contact you again but if they do, they'll be fishing for a reaction.
I'd like to think that at least one of them is feeling uncomfortable about this situation but it seems unlikely, sadly. So cut your losses and cut the adrift as friends.
For your DD - I'm glad that you had a nice evening but now is the time to have a conversation with her about the situation - she needs to know it's NOT her fault in any way that she has been excluded, but she also needs to know that it's NOT her fight either, and she's not to behave any differently to her friends until they start (if they do - not all kids follow their parents' directives).
Although this hasn't exactly happened to me, it did happen to an older friend of mine, when she was in her 50s!! She was a lovely lady, genuinely nice, kind person who would do anything for anyone. She worked in an office in a teaching environment - and then this other woman started work in the office. Within 6 months she'd managed to turn 2/3 of the rest of the staff against my friend, despite them all having known her for ages before and liked her - through petty spite, vindictive acts, claiming that my friend's niceness was "sickly saccharine sweetness that was disgusting to see in an adult woman" and other such things.
It was horrifying that these weak-minded individuals fell under the spiteful woman's spell, absolutely horrifying - and my friend ended up taking early retirement to get out of the stressful situation, despite the management doing their best to support her. Once the damage was done, nothing could ever go back - like the broken plate scenario.
If you don't know it, it's like this:
Take a plate.
Throw it hard onto the floor so it smashes.
Then say sorry to it.
Is the plate whole again?
No.
Once these things happen, it's very rare for them to mend properly.
So sorry for you that this has happened.