The most important thing about validating is that it is not condoning behavior and it is not agreeing. It is recognizing that the other person - as an autonomous, full being - has the right to say something and have their own thoughts.

So in asking your H "I'm sorry, I didn't hear what you said" you are simply acknowledging that he has something to say. Not that you agree or disagree. But that you see him as a person with independent thought that is worthy of pause and listening.

One of the top examples of validating is saying something along the lines of "Oh, I see how you could see things that way". And that's a misleading example, because it sounds like you are saying you understand their perspective from a personal standpoint. But what is actually being said is, "I see and recognize that you have this perspective". It's a subtle difference.

******
And I completely hear you with your thoughts on not engaging vs engaging. That too is a subtle difference and is even harder to determine when you're "in it". It's much easier when you talk about someone else's sitch.

I struggled too with the fact that I avoided/hid from all conflict around the time of BD, and even some times in our R when it was good. This lead to me not saying everything on my mind during the tumultuous days. BUT I honestly don't think me speaking would have changed anything. It very likely would have only lead to fights and hurtful things said.

You said it yourself - you don't think BD could have been avoided. Remember that point, because you're right.

And there's a difference between not being an engaged partner when you're in a true partnership trying to build a life together and sitting back now post BD. Post BD so much stuff has surfaced, and most of it is your H stewing in it all. Much of it has nothing to do with you in the here and now. So in most situations, just remember all the *(&)(*^ that H is fighting isn't your fight. You don't have to roll over and play dead but it will save your sanity to not engage. Your sanity is #1.

We get a very clear picture of our shortcomings from the R post BD. I see so clearly what kind of behaviors I should have stopped years ago, and I wish I had learned these lessons earlier. But I didn't, so instead I take them with me forward. I know that applying them in the immediate aftermath of BD would have brought me nowhere - and I absolutely got the "too little, too late" speech when I did try to change myself in those early days. Just be the best Woomba in a quiet fashion, and you will move through this as gracefully as possible.