LC I was interested to see your update about the OW's marriage ending and the emotional relationship continuing with your DP.
Has he now admitted physical infidelity? Or that the relationship was very much ongoing when you found out? If OW's marriage has now broken up, it seems likely that this is what her H must think, or she has ended her marriage because she now thinks your DP is free.
What I would reiterate to you again is that trying to reconcile when you still haven't had the truth is a bad idea.
And if you mean what you say, that if it wasn't for your DS, you wouldn't want to reconcile, do listen to yourself. Don't ever take him back because of your DS alone. Recovering from infidelity is hard enough if you know you want someone for the right reasons i.e. as a romantic partner, not for their other roles in life.
If you love your DP and would want him whether you had DCs with him or not, that's a good starting place, but only if he's being totally honest with you now and is willing to put in the hard work reforming his character.
The impression I get from your posts is that your DP is sorry that the shit has hit the fan and he is staying in a hotel, not that he is horrified at the hurt caused by his actions.
He also doesn't seem to realise that there must be an impenetrable wall between him and the OW and still seems to be putting her feelings before yours. If you've read "the book" you will have realised that she still has a window into your relationship and that cannot go on.
It seems like a lose-lose situation now, but really it is not. You hold all the cards now. You are financially stable, have a clean bill of health (Thank God), know now what has been happening to you in the past 2 years, have 3 DCs who adore you.
If you want to try with him again, be sure you're doing it for the right reasons and aim high in your list of conditions.
The worst bit of your life is actually over LC. That was when you were being deceived and didn't know what was happening to you and why you felt so awful. The power is all yours now, so don't squander it, will you? And hopefully you trust me enough now to know that this caution is well-meant .