Not sure where you are headed friend.
In one sentence it’s like you are determined to divorce, then the next it’s about reconciliation. Like why the MC, and why have a separation agreement if you aren’t intended on separating?
That’s OK – Most of us are really confused this shortly after d-day so there is no expectation or requirement of having fully determined where you want to be in a year. It’s sensible to have that separation formally lodged, but it’s a bit like taking your gun out of the safe because you hear noises in your house – you risk shooting someone unintentionally more than while it was locked away.
But I do want to suggest you do your best to cut out all the drama around you.
To calm things down – to your own advantage and for your kids.
Do that and it simplifies everything, and that in turn makes seeing your future easier.
Things like throwing out her dress and the rings, talking about MY house, MY car and all that... That’s drama. In reality chances are it’s marital house, marital car, marital asset, marital debt... things that neither of you can really keep the other in or from.
I’m going to suggest a couple of things to calm things down and probably make life easier for you.
Make all stakeholders clear on what is going on. A letter is overkill IMHO. It’s enough for most of them to simply know that you discovered that your wife was cheating at the time of marriage, invited OM to the marriage, and has admitted to other affairs since then. The last one only recently while in the family-car. That this discovery has completely shattered your thoughts on where the two of you were, and what a marriage should be. That it’s not clear to you if there is anything to salvage or not.
The goal of this is not to get people to choose sides or pass moral judgement on either of you. It’s simply to let everyone know what’s going on.
You can ask people to respect you and your decision, maybe even to help in making both of you decide correctly, but also make it clear this is YOUR issue and YOU will make any final decision.
Remove proven toxic people from your life. I’m mainly aiming at those that knew and helped or that friend who attacked you on the other site. You tell your wife that you don’t know if you will eventually reconcile or divorce, but that "friend" needs to go permanently. Her adherence to that requirement will be sort of a litmus test for if you might eventually think R is a possibility.
Clarify your stance with your sister. If this ends in d then it will 99% fall into the classic lines: Your in-laws will support your wife/ex wife, and you will need your family. You have enough battles to fight ahead. You want things to calm with her because you might need her.
Let your wife know what you are thinking. Like if you already have a filed separation agreement then that’s pretty clear IMHO. But let her know that her actions in the near future might sway you, no guarantee but things like accountability, fidelity and interactions with those involved in the affair (OM, friend..) will count heavily. No promises – but in might calm things around her.
Set her free. Don’t stress about if she’s meeting OM or the friend or whatever. If she is, it will become clear in the coming months, and that will tell you everything you need to know. Rather than YOU stress about her actions – make it hers to convince you she’s on the right path.
Finally – if you can adapt a mentality of what happened happened. All that’s in your power is how to move on. There wont be any revenge (other than you go and live a good life) or no way to make what happened go away. Things won’t get worse – even if you discover ongoing affairs or more dirt from the past. Any new discovery is simply info for you to base your future on – with or without her.