Invasion of Privacy?

Hi,
I work for a large company and I recently became very ill. I took a couple days off of work and went to the hospital a couple times. The doctors finally told me what I had and it wasn't anything really bad. I called my Human Resources manager and told her what I had and that I had to take a medical leave from work. I work in a very small department with only 4 other employees and 1 department head. The entire store has around 275 employees. A couple days later there was a meeting at my work. It was not the entire store but a department with about 60 people in it. My department head announced to everybody in the meeting what disease I had and that I'd be out for a while. That night one of my co-workers called me laughing telling me she had told everyone what I had. I also heard from another co-worker in my department that she was telling other people what I had like it was no big deal. The disease I have is not a big deal. The only problem is people who don't understand what it is exactly are going to think that I'm dirty or nasty. My family told me that what she did is invasion of my privacy and also defamation of character. Can I sue the company? I am very upset about this and I don't want to return to work because I know people are going to look at my funny now.

Thank you in advance,
T