I like to think of going dark/dim like wrapping myself in a cozy, warm blanket. It feels good to me and keeps me warm.
It must have been a blow to see him change the profile picture. (This is why I like avoiding FB). And it's sad that it seems like he's not doing so well. Hopefully he'll figure out at some point how to take care of himself.
I think you handled the interaction well and good for not replying to the last text.