First off, good for you for getting yourself help. It sounds like you are doing much better. I personally think your anxiety over returning to work is normal and understandable. I am in a similar situation but unlike you, I have decided to return on a part time basis and take it from there.
An ADON position can be looked at 2 ways - it may be overwhelming in what the position would demand from you OR it maybe just what you need to get back into the swing of things & to shift the focus away from all your past problems. I suggest not looking too far ahead..a job interview
is not a job offer so just concentrate on getting to the interview, seeing how it goes & how you like the place. I would NOT mention your medications/hospitalization etc. If you are asked why you haven't worked this past year simply tell them you were in a position to take some time off and decided to do so and to travel or whatever. IF you are offered the job and the drug test comes into play, it sounds like a few of your medication may show up so that is when and only then - would you need to say anything about them and keep it short - "I take this medication and can provide whatever is needed from my doctor" Why you take it is not their business - though some one here would disagree - most nurses know Xanax is for anxiety etc.
It sounds like you have been through a lot and are still on the mend. Nursing can be a blessing or a curse and the burnout can - and usually - hits all nurses who are in it for any length of time. You are not alone. Take it one day at a time and keep your health the priority. You will be ok. Good luck.