I need tactics to help keep him calm and to help him detach, without raging or painting me black.
Hey TrulyMadlyDeeply, I suggest you let go of any need to control his reactions to events. You can only control yourself, as I'm sure you know. Perhaps you need to work on your boundaries? See Tools, above.
I suggest you prepare yourself for an onset of F-O-G (fear, obligation and guilt), which is how those w/BPD attempt to manipulate the Non. My advice is: ignore or rise above it, but don't give in to arm-twisting. In other words, call his bluff as necessary.
I have a question: what is the best outcome for you? It's hard to tell from your post. What is your goal? Where would you like to wind up? It might help to define your plan, if you haven't done it already.
LuckyJim