What to do when wrongfully accused of cheating?
First, you should check and read the entire academic dishonesty statement at your university. This should give you an understanding on how the university normally treats these types of issues. Actually being proactive on contacting an office of academic integrity or student conduct, depending on its name at your university, can help you understand what the standard route for a professor to take for academic integrity.

While it is appropriate for a student to come to a faculty member to talk about another student's cheating, it seems to be a red flag for your instructor to ask others about your cheating by name.  A vague announcement about seeing that people are not looking at their own papers or looking at their phones is appropriate, but actively singling a student out for their academic misconduct could violate one's privacy in a case of academic dishonesty. This is something you should check with your university though.

Another person who may be of help is the undergraduate chair of the department in which this is occurring, but it seems in the comments you have tried.