Phizzy, I have been posting ex-JW stuff on Facebook for four years. My privacy setting is Friends of Friends, and I haven't been outed yet. One thing I did was to BLOCK every JW I knew. They are wiley-- using maiden names, no photos, using work town instead of hometown, etc. Systematically BLOCK them all!
I'm on Facebook for my kids and grandson. Live your life. Just be "cautious as a serpent" as they say.