Todays workplace can sometimes be a dangerous minefield, both for the employee and for the manager. You did the right thing in going directly to your boss and giving her a chance to fix the issue. I would also recommend going directly to HR. Company's in the US are in a constant state of fear regarding law suits and would likely respond to this particular issue in a rather strong fashion.

Of course, if you can find another job easily, sometimes discretion is the better part of valour.