OP, until they finish their investigating I would just go on and do my work as usual without telling anyone about your illness. Disclosing could possibly decrease the harassment, but it could also escalate it. Its a really tough judgment call not knowing what your coworkers are like.

Most people have problems in one way or another, and usually people will talk about it behind their back. I used to work somewhere where a woman would go and turn peoples radios off and do other things that people found annoying. She hated certain kinds of music. I'm sure she struggled with something (her son was also Bipolar, which she disclosed to me). She was so badly harassed at a certain point that she eventually just quit and moved out of the state.

The bottom line is that unless you absolutely HAVE to disclose such a thing, whether or not it is a protected class, it's usually a better idea not to. There is a rule of thumb that says don't tell people anything that you would not mind having posted on a billboard, because it WILL get out.

If the pamphlet sending was harassment, someone leaked the information more likely than not. Someone being in management does not necessarily mean that they are mature and responsible people.

If you have no plans to take action legally, I would go to work and concentrate on my job, stay busy, and go home. If someone was juvenile enough to do such a thing to you, then they will probably get some sort of bizarre satisfaction in knowing that it bothered you.