DG, time is on your side right now. Just keep that in mind. Just as I figured, when you backed off the pressure she resumed her deviant behavior. Now you have your proof. Keep getting more proof, not just for you but for the OM's wife. You are now building your own fantasy nuke and you need some more reality plutonium.
As others have mentioned, you want to catch her completely off guard. Your exposure must come in waves and be timed to keep your WW so discombobulated that she can't put out the fires fast enough. She will feel just a disheveled like you felt on your first Dday. Remember that day? How your world came crashing down and everything unraveled. You felt like you had no control, stuck in a swirling whirlpool reaching out for anything to pull you out. Your WW is going to feel like that if you execute this well. She's going to agree to your terms regarding custody and property just to stop the pain. You want to be ready for that moment when she bends to your terms.
Right now, write down the terms on paper/email for what YOU want out of this D (custody, property, staying in the home while she moves out) to give to your lawyer to draw up as a mediation agreement. Go find that lawyer soon.
Keep on the 180 and act happy. Keep looking for that job and get studied up on added skills.
Keep collecting evidence on the VAR and store copies in a safe place for the OM's wife. Yes, you cannot legally use it in court but you can definitely let his wife hear it.
Now that you verified where they are screwing around, you should consider hiring a PI to park in the garage and take pictures of them making out. Again, for the OM's wife and also so you submit this to your WW as undeniable proof. If you know anyone at her work who is willing to help you get those pictures then that's golden. Has she complained about certain people at work? Contact them AFTER you get all your ducks in a row and see if they are willing to help you be the "eyes and ears" at work.
Get your personal accounts ready for electronic transfers from your joint accounts. Do a couple of test transactions of $.25 just to make sure your personal account can receive the funds. You are going to execute a funds transfer (within your legal rights) right before her butt is served.
Prepare a packet with a statement as much evidence (pictures, your journal, info on OM, etc.) as you can to submit to her sister/friends/family. Make multiple copies. Send a copy to the OM's employer. I'm sure they would like to know what the OM has been doing on company time.
Prepare an age appropriate statement for your daughters.
Have the process server deliver the petition to her work. When she gets served, you'll either get a panicked call or a text from her. Send one text saying something to the effect of "caught" with an attached picture of her and OM making out, then go dark on her and don't respond for the rest of the day. If you know the date she will be served, make sure to contact the OM's wife on that same day or right before and give her the heads up on the A as well as evidence. See if she will meet with you and you can let her listen in on the VAR for further proof. See if she will keep quite until your WW is served. Also send the evidence packet to her sister and friends. Ask them not to say anything until your WW calls them. Get back home and start packing your WW's clothes and personal items in some trash bags and have them by the front door.
On nuke day, your WW is going to panic and talk to the OM to get their "story" straight. Hopefully, by that time the OM's wife kicked his ass to the curb and thrown your WW under the bus. She'll then call her sister and her friend with her version of the story. Hopefully, by then they have read your evidence packet already and will listen to your WW lie out her ass about you and they can call her shit out. Your WW is going to run out of places to hide and seek support. You'll be the only one she can talk to and try to bargain with. When she text you or calls you and asks "can we talk?" then you have her by the throat.
When she comes home that's when you whip out the mediation agreement. Have her sign it and tell her you MAY give her another chance and consider cancelling the D process but that you won't talk about it until she signs that agreement. Hopefully she'll be so desperate to gain some control in the situation that she will. As soon as she does, take a picture of it on your phone and email it to yourself, then store the original in a safe place, THEN talk to her.