Get all your paperwork together.
Sadly your marriage is already over.
Her having young children is likely the sticking point at the minute.
Get in front of this.
Get copies of all paperwork, banking, deeds, pension stuff together.
Get it safe.
Start looking around for recommendations for a good solicitor.
He may well bullshit you because the timing isn't right and he is in a holding position, but when that changes, he will be gone.
Be very very clear in your language to him, yourself and your family.
The marriage is ending because of HIS affair with a colleague at work.
Don't be moved from that narrative.
Stick rigidly to it.
When my friends sister was advised to do this, when they separated and he tried to then introduce her as a "new relationship" to everyone, after denying for a year that they were only friends, his family and friends turned on him hugely.
He is no doubt waying up his options and best move now.
He may be thinking he will actually be better to forego the conference as the timing isn't right.
Be very careful.
In his head he is likely long gone.
I'm so sorry, but better to be aware.