Here's what I did. I'm not recommending it per se (comes back to bite you in the rear) but anyway:
I shut off emotionally.
I refused to deal with any emotion.
I focused on logistics. Practical things. Getting the divorce done.
My experience was that with recovery (mine) and divorce, all my relationships changed.
Some changed for the better, some changed for the worse.
I dealt with that as I dealt with everything else -- looked at is as a business decision and took emotion out of it. People who sided with AXH and were working actively to convince me to go back to him -- deleted off my phone and e-mail and facebook. Poof. Not because they were bad people, but because I was plenty busy with my own life and really had no energy for trying to convince OTHER people that my side of the story was the sane one.
I would say it's paid off. A couple of friends I lost in the divorce have contacted me and apologized for believing his stories. One has a restraining order against him. Most still think I'm the wicked witch of the West. They're free to. I know differently.
I would take note of what friends support him and badmouth you and remember. You don't have to raise a stink about it. You don't have to get emotional about it. Just know you can't trust them.
As for the business part -- by all means defer to your attorney. But I would have no qualms about letting the feds know he's cooking the books. None whatsoever.