yeah, your situation sucks, but it's not all that unusual (for someone like me who follows the employment-law scene).
1. employers must do an immediate and thorough investigation of all complaints (so, just doing an investigation, although distressing, isn't a bad thing.)
2. according to recent guidance by the EEOC, employers should inform you about the charges and ask for your side (as well as ask you whether you know why the accuser would falsely label you a harasser).
3. if you don't get treated right, and soon, get a lawyer. a guy named MacKenzie was fired from Miller Beer after he was accused of harassment; he sued the company, the jury believed him, and awarded him $26 million.
4. if you want to know about your rights (or, rather, if you want to know what you could sue your employer about), here's a good little article listing the claims that falsely accused harasser can make against their companies:
http://www.mlb.com/artclaim.htm
good luck.