Hope ~ for anything that may have legal consequences, I wonder if you can take detachment out of your thinking process? It is really hard to weigh these decisions. Do you need to know what the letter was about? I don’t know the answer.
I do not recall the details of where you are in the process. I’m at a stage of extreme distrust while on the surface trying to mediate through things, so my advice is grey tinged for sure. I lean towards advising you have L advice just in case - a decent L would give you advice without pushing you to do anything. Perhaps you have no reason to be concerned and then could let it go
