Just got caught up on this thread.
@Started at 53 , that sucks! I hope you heal up fast.
Couple contrarian points -
Knowing how to fall is not a guarantee that you won't get injured. It's good to know how to fall, but shit happens to the best of us. Any one individual's experience is - just that. Or to put it differently, just because you hurt yourself when you fall doesn't mean it's your fault. Again, shit happens. Also, as you said, things can go real fast. Sometimes when I fall (not just skiing), it's like there was no in between state - there is "I'm fine" and then there's "I'm on the ground" - and I don't have any memory of the part in between.
Knee braces. After I blew out my ACL, I saw two docs. The first one doesn't ski - he said I should wear a carbon knee brace for a couple of years after the surgery. The second does ski - he said that braces have mixed results. They protect ligaments, but can increase the risk of damaging the meniscus in a fall. FWIW, while ligament reconstruction sucks - meniscus repair outcomes are all over the map, often not successful, and almost impossible to assess the damage and reconstruction chances via MRI. My personal choice was to avoid a brace - I know several people who started using one, and they never develop the confidence to ski without it. At this point I really have no concerns about my knee - it's not something I think about when I ski or when I fall, and I've had several impressive falls since I came back. But again, personal choice. You are skiing different terrain than I do, with different goals, at a different age. Now, a soft brace to give just a little support and compression - sure, why not? I've yet to find one that doesn't bunch in the back of my knee and get annoying AF, but if you can find something like that, it will keep the soft tissue a little warmer and more pliable, and the compression will just plain feel good.