You will get through this. You will survive. Quite possibly you will be come a better person for this. A better parent, and have better skills in relationships.
There is no logic in your MLC spouse. No logic that will make sense to you. Trying to figure them out is a waste of your time and it [censored] you in.
MLC is a process and a journey they must go through on their own. During this time they will make horrible choices from your perspective and others as well. They will burn bridges and lose the respect of people around them. IT is not your job to prevent this, you cannot.
What you can do is help them rebuild, later if you are around when they come out of it. You can support them, because they will be so fragile and broken. They will not believe that you could forgive them. You might not believe you can either.
Your children are not your support during this process, you do not use them against the MLCer. You do not make them into allies, you protect them, and you are their support. You do your best to kill the vicious cycle and prevent your children from going down the MLC road later on in life and doing this to another person.
You could get through this if only they didn't do this to the children. The children do not become your excuse to be angry at your spouse. You take on the responsibility of a single parent now and you become the best single parent in the world. Shower your kids with love, but, very important you also have the responsibility to raise good people later. Bear that in mind, do not over compensate. Your children will be ok as long as you are.
The OM/OW is a symptom. The numbers of MLCers who have PA are staggering, it means nothing. Do not ever compare yourself to the OM/OW. EVER.
Time. This takes time. In the time you will gain the skills needed to keep your balance. And you will want a level ride. One day the MCLer might say something that gives you great hope and the next take it away when you find out they have plans with the OM/OW for a clothing free weekend at a local BnB.
If they saying that gets your hopes up...be very very wary. Be suspicious and really do not get your hopes up. Because like a roller coaster, these 'highs' almost always are followed by a steep steep and fast decent.
It is your job to make sure the ride you are on is more like a float down a nice clam river and not the Tower of Terror at your amusement park.
In my experience the path back for the MLCer is NOT preceded by something amazingly wonderful like a statement of love, but a whisper of doubt.
You will snoop, do better.
You will make mistakes and go against the advice here. Get up dust yourself off and move forward.
LEARN. If you try something and it doesn't work, don't do that again, anytime soon. It might work later, but it certainly isn't going to work anytime soon.
This, all of this that you are going through? This MLC, your marriage...it isn't over until YOU say it is. You have the control in this. You have all the control in this. Your marriage isn't over until you say it is.
DO not look to far down the road. Just look a few days at a time. In some cases a few hours.
You will change your mind, many times. You will give up you will stand, you will give up. You are allowed to and you will have our support here.
2x4's here have a purpose. They are wake up calls, do not be afraid of them.
You are not a loser or a doormat. You are a person fighting for your marriage in the most unlikely way, by not fighting.
You cannot beat down an MLC, you can outlast it. The MLCer is going to hit you hard and hit you often. You are going to not be there to be hit (distance, not snooping, not trying to figure them out, not confronting about the OM) you are going to dance around and avoid as many hits as you can. And instead of hitting back, you are going to watch them fall when they are done, and if you are still around you are going to help them up and tend to their wounds. You aren't going to fix them, you are NOT the white knight, the princess/prince has to save themselves. But you can be by their side and show them love.
That is how this can end.
In the process, you will learn not to controlling, to stop being a fixer, to learn that while you do not NEED them in your life, you like it if they were.
They will come through this feeling like a monster, you will need to show them that they are not. They might have been, but when they truly come out they will think that forgiveness will be beyond them. You will need to show them that they are wrong by your actions.
This, all of this is for you, nothing here will fix an MLC...however, everything here can fix you.
Experience is a brutal teacher, but you learn. My God, do you learn. - C.S. Lewis
Life is usually all about how you handle Plan B. - Jack3Beans
Listen without defending; Speak without offending - FaithinAK