"He has just sent me the lyrics to Bastille's Bad Blood"
Haha this seems to be a trend with Narcs and an incredibly teenage thing to do - Go figure...
This is my Mini guide to begin to deal with these 'things' that somehow pass for a human. It's a bit mahoosive but yeah...add to if you feel like it!
Jekyl and Hyde.
That is what these 'things' are.
A while ago (if I could have bared the thought of looking at things face) I would have given 'it' the fucking dart board treatment.
Now, I do not give a crawling on its knees fuck (never mind a flying one) about what thing wants, thinks or 'feels'!
Do not in any circumstances let the thing talk to you on the phone - it's not worth the bother.
Don't bother with texts either.
Email for absolutely everything.
Calls only in an emergency and nothing more.
I would highly recommend buying a very cheap mobile or using an old one with a totally different sim card if you feel the need to communicate by text/call.
Name it the Twat mobile! 
Don't let 'things' know about anything going on in your personal life. Nothing. Nothing whatsoever unless...UNLESS it is 100% necessary. They will want to use every tiny last detail against you in very hilarious, sarcastic ways, insidious and spiteful ways.
It's always outrageously funny when this happens...Oh the anecdotes they could tell 
Do not let thing have the children in emergencies UNLESS, utterly, on pain of death, unavoidable.
Also, don't assume that the people they are seemingly charming will think they are charming...SOME will know or will soon find out what they are. Friends and family do stick up for 'things' and fail to see through 'things' utter bullshit even when it is staring them in the face. When it's glaringly obvious what is going on.
"Little Prince wouldn't do that surely?! What a horrible mother, what a horrible woman. No wonder you're having a hard time Little Prince. There, there. Let me reinforce your behaviour for you
"

I agree with a PP that the majority seem to be well educated however... they are emotionally 'challenged' shall we say. Void even...usually. Very, very stupid and immature in a myriad of ways.
Imagine having to pretend to be something you're not to those around you? It's all a façade. We know what they are and they're most likely afraid of that fact - hence the anger, bile, bitterness, hatred, contempt the things have for us - I don't know if that's the case but it would explain a lot!
There is no point explaining.
Absolutely NO point in emotional involvement on your part to try and express why you think they are wrong.
Nada. Zero. Zilch.
Does not compute. - it does not work. EVER.
Where kids are involved. Make it about the kids plain and simple, nothing more nothing less. Keep any or all emotional rationalising to a minimum.
To the things, the kids exist as part of them not as individuals. They are to be molded, not to grow and flourish in their own right with their interests and their thoughts and feelings in mind. The things may appear to make it seem as if they are thinking about the childrens wants and needs - they are not! I have found they often try to get the children to do what THEY did and what THEY enjoyed therefore the extensions of their beings must surely enjoy them too, right?
Usually, wrong.
If I could make viable a business filtering out all the shite that is sent to victims of 'things' in order to pass on the necessary (think a whole page down to a sentence, cos that's usually the case ay?) I would be in here and now with anyone else willing to opt in to a start up.
Fuck it. I'll do it for free.