I'm sorry they're upset with you.
IMO, if you had posted it on THEIR wall, maybe they could be offended, but you posted it on YOUR wall, and they are free to skim right past it if it doesn't appeal to them, ykwim? I think people need to stop cultivating a "spirit of offense" and not feel like they have to police what
you post on
your wall.
That said, I totally understand how conflict sucks for those of us who are sensitive to it, and I hope it blows over quickly.