I 100% echo what most everyone has said here. Not only that, but your situation is hauntingly similar to mine.
My WW had done 95% of the EXACT same things that your WW is currently doing. And man, I wish I knew of SI.com back when this was first started. Hell, I wish I had even a book on infidelity back then. I had nothing (didn't even know this stuff existed); I felt like I was completely alone and "unique" in this situation.
Had I had the resources you appear to have at the stage you are at, I would have 180'd my WW so fast it wouldn't have been funny. I would have put a stop to the continued abuse, lies, deceit, etc. Instead, I did what you are thinking of doing: I initially tried to "nice" her back into the M, and to convince her she was just making a mistake with trying to see her AP.
Man, let me tell you. It got so bad that at one point (last December), she was actually talking to me in the kitchen about her upcoming trip to see the OM. Yes, she was 100% communicative about it, thinking I somehow supported it. She was like, "Well I'm flying out on Monday to spend 5 days with him in his house in Las Vegas." I asked if she wanted a ride back from the airport, and no joke, this was her response, "Well, no, that might be a little weird, don't you think?". In hindsight, yes, picking up my wife from the airport after she has had a 5-day fuckfest might have been a little, well, strange, to share with my work colleagues around the water cooler the next day.
Suffice it to say, I had tortured myself with her continued abuse and betrayal until something finally snapped in me. I gave her an ultimatum, and was 100% ready for battle, so to speak.
The best advice I can offer is to start immediately collecting information (facts, etc.) on your wife's A. This will be incredibly valueable to you, should this escalate into something more severe that could result in a D with your WW (especially custody, alimony, etc.). Remember, everything of your wife's is yours, and everything of yours is your wife's. Do NOT feel "guilty" or "bad" about checking her email, phone, etc. You are a married couple, and are entitled to share each other's stuff, information, etc. If she feels offended by it, then they is either hiding something or has no concept of what marriage really means. Use a thumb drive or something to store all this information you collect (create a timeline-like document that has dates/times and actions she is engaging, like a log book, of sorts). Screenshots of messages on FB, etc. If you can find out who the OM is, find out if he is married. If he is, and ONLY if you have evidence that she is engaging in an EA or PA with this OM (e.g., FB messages that suggest anything sexual in nature, travel plans, etc.), then see if the OM's W is on FB (likely a FB Friend of his), and send her a PM letting her know that you have very important information that is highly sensitive, and that you'd like to talk to her. I recommend NOT sending what you know through a FB message, email, etc. Try to get her on the phone and tell her everything you know, and focus on the facts, not opinions. Bottom line, you HAVE to get this out of the shadows and out into the open. Your WW must know it is NOT acceptable to continue to emotionally abuse you and damage your family.
If you can, especially if she DOES in fact go to the beach with the OM, I would tell her before she goes that you know she is going to be engaging in an A while there, and that that kind of behavior will not be tolerated in your family home. If she then chooses to go to the beach, I strongly recommend drawing a hard line and contacting an attorney RIGHT AWAY. Use this time to build your case against her, and inform her that those kinds of behaviors simply are not allowed in your family, and that she must leave the house if she is going to continue those kinds of abusive behaviors. Leave it up to her to find where she is going to go, but inform her that you will NOT allow your child to be subjected to that kind of emotional abuse and emotional neglect she is inflicting upon her family. Protect yourself AND your child from this perpetrator.
If you'd like some advice on how to begin investigating and collecting information, please feel free to PM me. I would rather not post those tips and suggestions on here, as I know many WSs read these forums, and I don't feel comfortable with them learning some of these proven investigation techniques. The element of surprise is incredibly important at this point - let's NOT give her or others our "playbook", so to speak.
Best of luck to you. You are NOT alone. Keep fighting, being strong, and taking care of yourself and your daughter. Your WW is NOT your problem right now.