First 9, you absolutely did the right thing calling the cops and not talking justice in your own hands.
Obviously that was the "he has something over me" thing she did not want to tell you.
On anything else... maybe she wanted to come back earlier and was scared... and maybe not...
slow and steady.
Get a restraining order and no contact on the OM for you and the W and the kids. Contact a shelter for the W if necessary.
I'm sorry to sound harsh, but right now, bringing her back into the home is probably not the way to do this. If she has a place to be, and to be safe from OM, that's what's needed.
Then, you and your W can discuss the next steps...
