(Ex) Team Member still trying to harm my brand

I unfortunately employed someone while the business was growing fast and was in a rush. She seemed capable, charming and was very well spoken so I hired her on the spot without doing reference calls (bad idea).

This was a year ago now and I wasn’t super confident as a leader and really saw the best in people + would do everything I could to make my team the happiest they could be. Unfortunately over the past 12 months there were patterns of manipulative behaviour from this employee towards me – she took advantage of my kindness more than once, gaslit me and questioned my managerial style in front of the team.

I have a really good relationship with everyone else in the team – they were the ones who told me for months to let her go. I didn’t for so long because of the fear of unfair dismissal (australian employment laws are very strict – you can’t just fire someone due to bad fit or behaviour unless it’s all properly documented continuously and even then it’s merky).

Finally there came an incident where she tried to manipulate me into something that I knew wasn’t right and i stopped trying to cater to her/stopped giving her the benefit of the doubt. As soon as she realised I wasn’t going to cave/she no longer could manipulate me – she quit.

what I’m frustrated about is I’ve been civil with her despite the hell she put me through, have given her so much, have only ever tried to do what’s right for her despite the things she did against my business, my team and myself – but she’s still talking negatively about our brand to people she knows and even my team. She shares stories and posts on her social media indirectly accusing my brand for not putting mental health first (which I do take very seriously so it’s really upsetting).

I know I can’t control what she does, but it’s frustrating 1) that I keep thinking ‘I did everything for her, why is she still trying to hurt me??’ and 2) to see my employees who were the teammates that complained about her, still friends with her on socials, liking her pictures etc. when this individual is trying to negatively affect the brand that they work for.

I really just want to drop it and move on – these things happen. But the 2) thing is really getting to me. How do I let this go while also letting my team know that I’m upset they haven’t stood up for themselves or me.