Even knowing what a beige eating, financially abusive cockbrain he is, that must still have been an incredibly painful discovery.
He has consistently underestimated and undervalued you - and the satisfaction when you take him down is going to be immense. He will no longer have any influence over your girls - it will be you, their amazing Mum who will be able to raise them so well, and they will thrive.
Practically - did he hint at divorce to his AP? Is it likely he has been getting his ducks in a row and speaking to a solicitor as well?
Have you got access to joint funds? Have you got enough to live on? To pay the mortgage incase he stops paying? Have you managed to see / screenshot all his bank balances - does he banking apps on his iPad? And have you searched for any other evidence of investments he hasn't mentioned?
Are you going to go after him for financial abuse as well?
I'd send you strength but you are an absolute warrior and this anger will no doubt fuel you to rebuild the most incredible life without him.