Today is your new life
Use today constructively,
Find all the paperwork relating to the house, pensions, shares, accounts his and joint ones.
Passports, birth and marriage certificates
Get it all dropped off at a friend's house.
Can you access his emails, phone records, you have her number at least you can gauge when it started.
Block him on everything except email. This will stop the late night, after a bottle of wine,I miss you texts.
At the moment he is riding high, he has his new GF and he isn't giving you a second thought.
Soon he will land with a bump, when he realises how much this is going to cost him in the divorce.
As soon as that happens he will come crawling back to pacify you.
Keep strong