Is there more resource than DR on 'how to deal with S, if someone filed for D or is about to?'
What are you looking for? More guidance on how to act? You seem to have some difficulties already following the DB advice, often being quite emotional, unsure about everything and not staying on track. It seems to me that what you need most right now is to be centered, calm and trust the process. It will get worse before it gets better.
The other thing is that you don't have control. It's not about finding another method or piece of advice that will magically give you control to stop the D. All that I've read and heard aligns with DB: let go, focus on yourself, detach, etc. There's no silver bullet.
M39 D6 D3 (at S) S 2014-09 D 2016-09
"You can't start a fire sitting around, crying over a broken heart" - Bruce Springsteen.
