Adultry and divorce case to be filed

Hi i have lot of physical and mental issues with my wife and we were not together for more than a year. But i had an relationship with a girl who is unmarried and my coworker. During a family function with my relatives support my wife took screenshot of My conversation with the girl. And i was planning for divorce. And my wife also not interested in living with me from beginning however for revenge sake they are blackmailing us that they will file a complaint in women police station with the proof against me and that girl. And i dont want that girl to be involved so we got an idea to get legal notice from the girl that we were not together and to not bother her in any case. So how to move this situation to divorce and how to get solved from the complaint they are going to file in womens police station please guide legal advice. Thanks