A disgruntled ex staff member

I had a staff member who voluntarily resigned from my place of business. However, this person made it seem like I had terminated their job prematurely. This person suspectedly had given my establishment a negative rating on Google reviews. I am not able to confirm whether that person who has reviewed was my ex staff member because they had used an unfamiliar user name. However that particular user name suspiciously sounded like their name in reverse. I just want to ask whether I should approach that person or just ignore it as that review could potentially cost my establishment's reputation.

If the review has the potential to ruin your business & your reputation, then you best go legal with it all. Google can then help you sort it. Given the circumstances as you post them, you'd be well advised to have no contact with your ex employee.