arbuom, I am you 5 years past my Dday. I had a 17yr M and two boys that are 3yrs apart. My XW was initially caught in an EA but never acknowledging it. I suspected it went PA and could not get proof until the OBS contacted me and gave me the evidence. Later the OM in my situation finally admitted it was a PA. My XW still to this day denies an A ever happened, only acknowledging that her talking to the OM about our marital issues were "inappropriate". Anyway, I got the same ILYBINILWY from my XW. When I asked her how far had she known that she stopped loving me, her answer started with 2yrs ago. Then it changed to 5yrs ago, then 10yr, then "I don't think I really loved you since we got married and then finally "I never likd you while we dated." The logic is insane, isn't it? This coming from a woman who I had two children with! However, what my XW and your STBXW is experiencing is cognitive dissonance. It is attempting to compartmentalize two conflicting trains of thought, beliefs, images of themselves, etc. It prevents their ability to understand the difference between lust and love. She said she doesn't love you, but still stays. My XW actually moved into her own apartment and left so her actions backed it up...to a point.
So, from my own experience I'll share some of what I have learned so far -
Yes, arbuom, it is very likely your WW does love you. She is just burying it 6ft deep to quell the dissonance and what it is buried under is a shit ton of her rationalizations of why she THINKS she doesn't love you. You can bet that the OM was right there with her shoveling some of that bullshit into the grave. She will likely try and shack up with that dipshit OM during your separation or after the D is final. She will begin to realize even though you are no longer in the picture she is still unhappy and the OM is all talk and short on delivering. This is where it starts to hit her with that old saying said in so many different ways "You don't know what you had until you lost it". I don't explain this to try and persuade you to consider R. Just that her motivations, like DarkHoleHeart explains, are going to change once her fog wears off so make haste on getting that D going.
Also, mind what MidnightRun stated - "She thinks you should be falling to pieces over the thought of losing her." At first my XW thought she was just the modern day Venus with all the sudden work outs and shopping trips to victoria secrets. When I got that ILYBINILWY speech I was doing the pick me dance, but it was more like "pick me over leaving and being single" I had no idea at the time there was an OM in the picture. Once I figured out there was an OM and a PA occurred then I knew my deal breaker was confirmed and I moved toward D. I 180'd her ass like I won the lottery and was going to go live it up as a single man again. I dropped 60 lbs from my "infidelity diet" as they call it here started working out more and looked better than I was when I was 17. Other women are going to notice you if you have already been noticed. Then your STBXW is going to notice that other women notice as well and may very well begin to hoover you hard back into the M. My XW tried that. I shut it down.
You say you want an equitable D and think she should have her "fair" share of the assets. You should really tell your attorney you want what is best for you and your kids first and foremost. Your WW is going to get her own attorney anyway. Ask about collaborative divorce if you haven't already. Ask a few attorneys about the mediation process. Then, let the attorneys guide you on what is "fair". Yes, it can save time and money. However, if your STBXW's motivation changes as explained above she WILL still attempt to make the process contentious. My XW tried to twist facts and control the mediation when she realized the D was really going to happen.
Be the rock for your kids. Here is the key, be the same dad to them that you have always been but just be the best version of you. It should be easier because all the time time, energy, focus you've spent on your STBXW can now be diverted to your kids and they are going to need every bit of it from you during the D process. Your STBXW is going to be the loopy one and you want her demonstrating that behavior in person, in texts, in emails, voicemail, letters all delivered to your attorney the moment she unhinges. This can be leverage even in mediation when discussing custody. You will want YOUR place to be home to the kids, their safe place. Hopefully, your STBXW gets her shit together to realize she needs to pull the same effort as you for the sake of your kids and the best part is you are already going to be setting an example of how. Go talk to the kid's teachers and explain the situation so they can be prepared and accommodating when your kids are having trouble concentrating at school. Get ahead of the process and research some IC for them as well that specialize with children in divorce situations. When talking to them, let the be angry at you if they are about the D. You want to be that parent they feel safe showing their emotions, good or bad. You will very likely strengthen your bond with them through this process.
Don't be afraid to ask for help. Reach out to your family and friends. Start working out some logistics with getting kids to school and their activities, where they can stay until you can pick them up from work, setting time for them to hang out with their friends, etc. Don't try to shoulder the entire single dad effort. Take advantage of whatever assistance you can get.
Do take care of yourself. You are right, arbuom, you didn't deserve any of this. No one does. If D is your way to make it right for yourself then that's what it takes to get you on the path of healing. Besides, you can always change your mind anyway. D can be stopped any time. Just know that marriage is but a contract and that its dissolve doesn't mean permanent banishment from your STBXW. That fact you two have kids together pretty much ensures you two will remain in contact until the kids are legal adults so there is time to observer her from afar and see how things turn out. People here have gotten back together after D and even remarried.
Don't fear the dating scene. The problem won't be if any woman will want to date a single dad. The issue will be figuring out which ones are normal from the crazy and desperate. The most shocking revelation from my own D is realizing that being a single employed father who has his own place was GOLDEN. Now, there is no rush to date. Shoot, you don't have to date at all but do consider pushing yourself to be social and participate in events in groups or with friends. Try not to be a hermit. Your kids want to see their dad be happy again. It is for their well being also to see you pushing yourself forward and being happy again. They learn by example.
The sooner you step towards better days is how soon they will come. So don't think of this as "Starting over again" Instead, think of this as starting anew for a different life adventure for you and your kids. Yes, it wasn't what you always thought it would be but neither did a lot of us that moved forward to D and started their new beginnings. But, how that turns out is very much dependent on you and the way you want to look at the future, either with dread or full of hope.