Does she have evidences that you had s*x with her?
Right as now, all you can do is deny all allegations. If you are getting calls, then ask your wife and ur daughter to file a police complaint against her for harrassment
If you are sure that she cannot prove the s*x part in court, I would suggest that you start with IPC 499 right away. This would probably deter her from filing a case on you. If she does proceed to fila case, you can always claim that it is a counter case.
Remember,.judges are in women favour, so I would suggest that you relook at your evidence, whatsapp, emails, SMS, phone calls etc to ensure that she is unable to prove adultry.