Once the cats out of the bag, fuck it.... although I think you would have to keep the provider/client relationship as professional as ever. If you're her boss, pay her rate, don't expect special privileges. Also neither party should make any comments in public that could be construed as anything but professional.
Could be a lot of fun if done correctly!
I know a few providers that come into my work, but they don't know I"m a client, so I'm not taking any chances... but if they found out, it would be nice...