Hi Rachel, I apologize for the delay in my response. While I can definitely understand and respect your concern for crossing boundaries, I would be very surprised if your actions caused your doctor to stop working with you or treat you any differently than he ever has. Most likely this is not the first time someone has attempted to friend him on facebook, and since you immediately deleted that, that seems to demonstrate that you aware of the boundaries rather than you are attempting to violate them. You can certainly apologize if you feel the need to, but I wouldn't otherwise think that it's necessary to even raise the subject unless he does.
It would be very different if you started sending personal messages to him, or persisted in trying to contact him outside of a professional environment. Most doctors are aware that many of their clients do not even understand patient/doctor relationship, and run into far worse situations than this. Most times they are able to discuss this with their patient, and continue the professional relationship without any problems.
It's good to hear that you've been able to go back to work with the support of your doctor. You've obviously made a lot of progress. However, if you've lost your confidence and find yourself so emotional it may certainly be worth your while to discuss a medication to help you cope in the short term. Overall though, I wouldn't let this recent facebook incident add to your anxiety
level. If you need to clarify that with him and ask him not to ditch you for your own peace of mind that is understandable. Otherwise, it is something that many doctors have experienced at one point or another, and should not affect your ability to work together.
I definitely wish you the best with all of this, and if there's anything else I can do to help please let me know.