Talk to a lawyer asap. Don't do ANYTHING before talking to an attorney. Don't discuss anything with her, don't move out, ANYTHING. If she hasn't filed you can take financial steps to protect yourself. Plan on being a ruthless fuck because if she does and you don't, you are in trouble. In my divorce, the judge split assets 50/50 and liabilities according to income. Not Assets minus liabilities and then split the difference but he split the assets 50/50 and gave me the lions share of the liabilities. If I had known this beforehand I would have liquidated assets to pay off liabilities. So talking to a lawyer is a must. If it's not too late, do not tell her that you know. Knowledge is power and if you can keep her from filing it gives you more time to prepare. You can always be the bigger man when in a position to be the bigger man.
Get a PO Box. If you are required to stay in the house you are going to receive mail that you don't want her to have access to. If you take my advice and start positioning yourself before filing or even letting her know you will want any mail to go to a PO box. Transfer your bank and credit card statements to the PO Box. If you need to retain an attorney (you do) you won't want anybody to see that charge.
Get all financial information out of the house. They can get what they are entitled to from your attorney.
If you have kids, you need to decide what you want. Do not hire an attorney that tells you that you can't get what you want. I wanted 50/50 joint custody of my kids. I had to interview 5 lawyers before I found 1 that said I would get that. It cost me $30,000 in legal fees (including her legal fees) and had to go to trial (less than 10% of divorce cases go to trial) but I got the custody I was seeking. Keep them out of it as much as you can. Don't discuss things with them or badmouth their mother.
As @NextStep pointed out, take care of your mental health. This is going to be a rough year at a minimum. I had to live in the same house as my ex during the entire divorce because of the custody situation. I started meditating and went to a therapist. It was a life-saver when she was screaming at me in front of the kids and I wanted to punch her in the face. I was able to remain calm and just take it.
At this point assume everything is being documented and recorded. Don't lose your temper, don't do anything without speaking to an attorney. Hopefully, she isn't multiple steps ahead of you at this point. If you can record interactions with her it may be helpful if you are accused of something. Lots of men are accused of abuse in custody situations (I wasn't) and good fucking luck disproving that in a divorce case.
That's all I can think of off the top of my head. If I think of anything else I'll post it. All of this being said your best outcome is going to a mediator and working thru things amicably but the chances of that happening are greater if you have the upper hand legally.
If you need a break or just need to get away my house is open to you. We are probably on opposite coasts but if you need to fucking disappear for a while to clear your head or just to take a breath let me know.
