I'm sorry that there are those limits on your greeting this student. Of course we can't tell you if you have a mental illness or what that might be, but from what you wrote you may have OCD and depression? And that this has happened before? Crying because of your boss talking to you could be related, but maybe also it is just upsetting. I don't think that anyone feels good after a boss tells them to stop doing something. It's kind of embarrassing, and maybe disappointing.