I think we are focusing too much on the wrong issue.
I like comparisons and similes – and sometimes go overboard with them… But this discussion on who cheated first and all that… its like realizing once you reach your remote destination for the wilderness camping-trip that you don’t have matches or a lighter. You can argue all day long with your wife over whose job it was to bring the matches, but even if you eventually agree that it was her role (or yours…) it still leaves you with the same problem: No fire, raw food, and cold coffee. It would be a lot more productive to start thinking solutions – ranging from rubbing two sticks to packing up and giving up on the trip.
Right now the issue IMHO is not who cheated first. If I was a betting man then I would place money on there being some romantic reason for the ILYBNILWY speech when she left. But… that would be an assumption.
The problem I see is that for some time you and your wife have been having a quasi-marriage. A Frankenstein-like marriage (see… simile!). In this quasi-marriage you have no way to adhere to marital conditions, yet you have expectations of marital obligations being met – both of you. I think THAT is the big issue. An unclear destination. It’s obvious in the had-sex-with-someone-else aspect, but it also sounds like there is emotional infidelity, financial infidelity and the "in sickness and in health" obligation not being met. In other words: there are big issues in this quasi-marriage.
To me that is not sustainable and to me that is the big problem.
I want to emphasize a couple of simple truths: Your marriage can never be healthier than you are.
Your main focus should be YOUR health. Physical and mental. IF this marriage survives it will be YOUR mental fortitude that carries it through the first stages. If it doesn’t you will need to depend on YOUR mental fortitude to get out. So focus on YOU first and foremost.
Second truth is that IF this ends in D you will be fine. You will survive. Rule-of-thumb is that 2 years from the divorce people are doing emotionally fine.
Third truth (as I see it…): Divorce is not the worst outcome. It’s one of the two outcomes we can use to survive infidelity: Divorce or reconciliation. The absolutely WORST outcome and the one to avoid is where you two live together as a couple without ever cleaning up this mess. It’s where you even share your wife – physically, emotionally or even both, with someone else and you pretend to believe her when she says she is going "shopping" all dressed up on a Saturday evening. SHARING your wife and/ or living in UNTREATED INFIDELITY… THAT is the WORST.
I suggest you consider this:
Take a good think about what YOU want. Like do you want this woman as your wife? If the answer is yes then think what you need and what you can get. It’s like if you want to win the lottery – you can get a ticket and that does give you a weak chance of winning, but it would be a terrible idea to go buy a house based on your probability to win next draw. So base the what you want and what you can get on REALISTIC grounds.
To get this out of the way: To divorce all you need is that YOU want to divorce and/or that your wife doesn’t want a marriage. [As you see marriage. She MIGHT want to remain married while living separately and you two try to one-up each other withs sexual partners].
Remember that divorce is the separation of two lives. Her financial situation, living situation etc after signing is of no concern of yours. The laws are relatively fair, and you will be FINE a couple of years after the Big D. D is not an admission of surrender, nor is an attempt to R required before you file. D is simply an admission that what you are being offered isn’t what you want.
If however you want this woman as your wife…
Then the first thing to do is to get it clear from HER if she still wants you as her husband.
Note how I didn’t say "if you want this marriage" and "if she still wants this marriage". I think you two both need to look at the "old" marriage as dead, and whatever you do now needs to be seen as new.
I 100% believe that in order to reconcile you both need the truth. That includes you fessing up to your encounters with your GF (that your wife already know of btw), but it also includes your wife letting you know why she moved out. Not the ILYBNILWY but WHY. Why wasn’t it "we need to work on our relationship" or "I demand change or we divorce" but rather ILYBNILWY and move out? That’s drastic… that’s like comparing your situation to a conversation between Gacy and Bundy… (see? Another simile!). I also think you 100% need to know who the OM is. After all – it could be your mate Jack or the guy next door or whatever. A major part of recovery is accountable NC with the other person, and without knowing who he is there is no accountability… BTW – that goes both ways, so your GF is out.
Once you have the total truth you know what you are dealing with. It does require a lot of "forgiving" (as in not automatically divorcing or having a R affair if the truth hurts) and it’s possible that the truth reveals something that makes you not want to R, but IF you were to create a new marriage it needs to be from THAT truth.
OK – The issue IMHO will be that she’s not clear on what SHE wants…
Well… To use one more simile that’s like being indecisive when parachute jumping. At some point you need to pull that cord. Until and unless she clearly tells you she wants a marriage with you… she’s clearly telling you she doesn’t. If that’s the case then continue with the process of preparing, and eventually filing for divorce.
Finally:
This site has relatively few and simple guidelines. I encourage posters – maybe especially first posters – to read those guidelines. If you think them stupid or excessive or whatever… there are other sites. But then – they generally have very comparable guidelines. Going round site-rules and guidelines might make you feel smart, but definitely doesn’t show you up to us as being smart.