Like I said before, just keep to the truth.
Do not stray from the facts of this.
He told you two days ago it was all over without warning, and its been a massive shock. He hasn't said why.
That ^ is all you need to keep telling yourself.
If he is trying ro re-write history (umm, yes he absolutely is), just go back to your basic facts. Tell them to anyone and everyone.
Do yourself a huge favour, give him a new email address to direct all and any communication on, advising you are blocking all your others from him, then block his phone number and usual email from his contact.
It might be an alien concept to you, but his is now out of your priorties list, you are top, then your dc.
Keeping you happy and safe from his head mess will also keep your dc free from it.
You have to step as far away from him as possible.
Let him know that you will be checking his emails at a set time (whenever is best for you, and only chsck yoir email then that best fits your schedule).
Being utterly selfish about this is good for you, and by association your dc.
The painful emotional processing of what's he's done you meed to take your own time to do, to care well for you.
He has treated you like utter shit and is no longer your friend or any other type of ally, but your enemy.
If he'd behaved honestly, put his dc first, painted an accurate picture of your relationship and showed you all the respect you deserve, this could be different. Its not.
Take control.