TheLostOne2020,
I am very sorry that you find yourself in these horrible circumstances. I posted some of the comments below on another thread, but I feel that they are equally applicable to your situation. As always, consult your lawyer so that you do nothing that is adverse to your legal circumstances.
You are in the right mindset as you have now decided to move to the end-game. File for divorce and/or have a filed separation agreement where terms and conditions for boundaries are clearly set forth, that your financial affairs are segregated, and custody arrangements are clear (access for you and NC with OM at all for kids, etc.). At the least, have your lawyer serve her with a letter informing her that the 365 day clock has officially been started. You need to do something (!) seriously symbolic that she has started the beginning of the end. That makes the fact that you will divorce certain.
Your children will also see this as an act for which they can respect you. They are young, but they will get it when they get older.
You owe her nothing, you don't have to deal with her at all. You can ask that all further communication be only about joint finances and the children and should be through your attorney, by email or text only, or any means that you prefer.
Unless you decide to move in with your parents, or find another home for you and your children, tell her, in a cold steel whisper, that she is not welcome in your home. (That is not demanding that she move out. You are just strongly suggesting that she do so.) She has terminated you as her husband and now you owe her nothing, and will give her no time, no attention, no support, no favors, nothing. (Except for matters regarding the children). When she tries to engage with you bring to your mind Rhett's parting words to Scarlett, "Frankly, my dear, I don't give a damn."
I suggest that you consider the grey rock method (or "arctic zone 180") , where you become emotionally non-responsive, boring, and virtually act like a rock. The grey rock method takes away any and all vestiges of emotional "kibbles" and attention. It separates you from any further emotional damage and starts you down the path of a good, happy life without her.
In order to implement the grey rock method, a person needs to minimize conversations and verbal exchanges as much as they can. While interactions should always be avoided when possible, any contact should only relate to joint finances and the children's needs. You should reply with minimal and short responses to limit further conversation. You should try to only provide one word answers without elaboration or opinion. You can utilize nonverbal responses such as nodding and smiling to avoid further engagement.
It is important that you use the grey rock method never provide any details regarding your personal life. It is critical that you do not communicate to your STBXW what you are doing without her. You should only respond with facts whenever possible, as facts are difficult to challenge or argue. You should stay away from discussing the past, as old arguments can be resurrected.
I think now is the time you take your ring off, if you have not already. That will send a powerful message to her that you are done with her betrayal and disrespect. You owe her nothing. Since she "fired" you, you should not wear a ring which is an emblem of love through time, a symbol of devotion and an agreement between two parties to love and cherish one another for the rest of their days.
Please cut her off from all financial support by you. Cancel all joint credit cards. If you have not done so already, set up a separate bank account for you. Make your deposits to your account which she can't access. Make sure that all marital money spent on her affair/OM is accounted for and reimbursed by her in any financial settlement. Consult with your lawyers about your not being liable for any debt that she incurs during separation.
She is egregiously unfair to her children to subject them to her horrible behavior. Can you arrange via any Assistance Plan or health insurance for some counseling for them? Perhaps their schools or your church can provide some support. Think about keeping them close to you, doing fun things together while excluding your WW. She left the family, she does not have the right to be included in your activities with them. She does have parental rights. Discuss with your lawyer how those parental rights can be managed. Insist that your wife keep OM away from them - no introducing him to them as part of a new family unit. Keep up the cold steel 180. She has fired you as husband, do not provide any emotional or financial support at all. She has brought all her shame upon herself. You had nothing to do with it. The same as she had done to you, put her in an arctic zone and you stay as cold as an ice cream cone (Rolling Stones reference). Keep your VAR on you for your protection.
If you do a same house separation, I suggest that you do grocery shopping for yourself and your daughter. Do not shop for your wife. Tell her that she is not welcome to the groceries that you have bought. Label the milk bottle, creamer carton, sugar, coffee, bread, and everything else (including the package of toilet paper) with a black felt-tip pen as Dad and Daughter ONLY (or just "DD"). Every time she opens the cupboard or refrigerator she will get a totally unambiguous message that she is not welcome. Whether of not she ignores the labels and "steals" your groceries (think of what she has already stolen from you), it is the message that matters. Typically, the actions that I mention in this paragraph would be considered petty. But, I think now is the time for the message to be undeniable and persistent that she is not welcome around you. I also suggest changing the wifi password, unless she pays for 1/2 of its cost. Also, shut down her mobile phone if it is on your account. She needs to go get her own.
Normally I would not be so petty, but her egregiously selfish cheating and attempting to protect her "cake" at your expense, in front of you and your children, justifies your stark, cold ghosting of her. If your WW doesn't get the message and defiantly remains in the house, I like the idea of your moving to your own apartment with your children, or moving in with your parents, but first you should consult your attorney wrt custody issues and physical separation arrangements.
Again, normally some of this would be extremely petty, but now a "shock and awe" message is needed to make sure she understands viscerally what she has done to you and your family. She is a cancer that must be cut out. A same house separation is a one-year sentence of misery for you. She doesn't seem to care and can continue to live with her despicable self, thinking that you and your children are just collateral damage (if she thinks of you, at all).
Please take full advantage of your network of family, friends, and SI supporters. Feed off their positive energy and their care for you. Many SI posters have commented on how wonderful exercise (particularly weight lifting) is to reduce stress. It is also a great way to stay away from your wife and do something fun and healthy without her. Have your friends come over to spend time with you and keep you occupied. Maybe, have them over for the Super Bowl. You don't have to invite your WW to participate. Let her watch the Hallmark Channel in her bedroom.
From KingofNothing:
You’re not paying for gas or maintenance any more. She can change her own oil. Take her off your insurance and notify her of the fact, you don’t want her to drive uninsured, but you don’t have to pay, either.
Always remember,
1. The opposite of love is indifference, not hate.
2. Your goal is to heal yourself and move away from infidelity.
3. Always have a VAR on you for your protection from a false DV accusation.
Sending strength and support.