I always think its good that the more experienced walkers post reports like this. I think its a powerful message to us all that these hills take no prisoners and can be savage as well as stunning.
I can remember the feeling of panic myself when my jaunt to the south glen shiel ridge last year went all pear shaped. Walking off the hill in the dark, tired (well, exhausted by the end), with mist and clag rolling in and visibility as you described with a headtorch being nil was not fun. Thankfully for me the route was always going to be relatively easy to follow, but once your head is messed up that doesn't always matter.
And thankfully you made it out of your experience in one piece
- and there can be no shame in benefiting from the excellent support of MRT. At least you were well equiped, unlike many a tourist that goes a wandering from time to time and is needing to be rescued.