I wouldn't be embarrassed. Whether or not other people saw it, it is Facebook. On Facebook, people are always kidding around and joking. Anyone who saw it either just thought that you were playing along, or were fooled (which, judging by the comment this friend made wouldn't be that hard; and I don't think that it would cause anyone to think anything bad about you). I see comments on Facebook like that all the time, and I hardly give them any thought. Again, it is Facebook, no need to be so serious (which is common for an aspie).