Ina, they are my thoughts too, although, not too sure if I have said this one before BUT, one of my ex bosses was fantastic, still have him as my FB friend, he always stopped and made a cup of tea when stress was building, he used to be a psychiatric nurse.
Anyway, we had some jobs going, my boss was on leave at the time of interviews but the new candidates were chosen, then they all dropped off details, photos, passports etc to go into the records and also to get starting dates once checks had been done, my boss had a shock as some one who was a full time patient actually was given the job, he was not even fit enough to be out in his own accommodation, he was still going to be employed but he himself chose not to take the job offer.
Also, they do not need to know your medical problems, but I know they can put things together, but, all they want is some one suitable for the job, they should ask questions and if you answer them correctly then you have the same chances of any one else.
I worry about my husband as well, he more often than not, says the wrong things!!!
I also know we have spent money on interviews that we cannot afford at all....I truly hope it goes well for you,

and its the same when they see physical stuff, although they should not discriminate, they do!!! I often got given stuff to do that was very difficult for me when other jobs were easier and more suited.....no one made it better but plenty made it worse.
Mental illness Can be hidden but physical stuff cannot!!