You said the job didn't work out due to your having a mental breakdown. Ok we need to deal with two very important questions up front.
2. Were you actually hospitalized for any period of time during your breakdown or were you released to go
home with your family. This might seem like a silly question, but I am asking simply because these situations
may vary... and also because this is the kind of thing that could possibly come up during a background check
should you be selected for the job. I say THIS because depending on your diagnosis, prognosis and
overall situation, your doctor may or may not be obligated to release certain info about you. I don't know, but it
would be a good idea to look into this just in case.
3. Did you leave the second job of your own accord after the breakdown occurred and during recovery... or...
did your previous employer let you go right after the onset of the breakdown)?
4. How long have you been unemployed at this time?
I am not trying to put you on the spot, and you don't have to answer "me", but you need to at least deal with these questions within yourself, AND remember that you are not obligated to share personal medical information with anyone during your interview process so it's OK to generalize or refer to it as "personal reasons" for now, but you would have to divulge certain information if you were ALREADY working for these people and your mental situation results in a temporary and/or long-term leave of absence. Now... if your recent your breakdown (or episode) was extremely severe, then I will reiterate the fact that it may be possible that your doctor may or may not be obligated to release certain info about you during the standard background.
That's all I've got. Lot's of luck.