If you had been talking about a male employee I would have thought you were talking about the very same person who did exactly this to me.
It was a waking nightmare and despite professing their support my employer was utterly spineless in standing up to what was in effect workplace bullying.
My perpetrator was a person in a team managed by one of my colleagues and this colleague was in tears at the prospect of having to hold a meeting with him to discuss him bullying someone else on the same grade as him in her team so I was asked to run the meeting with her as support.
At the meeting she wimped out and said nothing so I had to say all the things which needed to be said.
He was furious and so made me his next target.
He an ex union rep (ex because they had sacked him because he was such a trouble maker) and knew every technicality you could imagine.
He had previously been disciplined for bullying the manager before me.
My employer let him tie them in knots and in the meanwhile I was living in limbo.
It took almost a year and in that time my mental health completely broke down.
I went from a strong manager who had always had excellent feedback from above and below to someone who couldn’t leave my home.
The bully was emboldened by my employers weakness and went further and further until he was actually following me about my workplace and encouraging others to make complaints about me.
I had silent phone calls at home and my tyres were punctured.
During this period it came to light that he had been charged with harassment of an ex partner and had been due in court but he had persuaded the ex partner to drop the charges.
Eventually his grievance was not upheld and he was told he had no evidence at all for his accusations.
He then took out a grievance against the person who heard that grievance and went off sick with stress.
He was never held to account because my employer had a policy of not disciplining someone on the back of a grievance.
Clearly this policy had not properly considered the use of the grievance system to bully by means of vexatious claims.
Eventually he was found to be moonlighting in another job whilst claiming sick pay from my employer but was given the opportunity to resign instead of being sacked.
He resigned and so is probably out there now making other people’s lives a misery.
The only lucky thing for me was that I was in a union. They were fantastic.
We brought a case against my employer for personal injury which eventually (six years!) settled out of court.
My advice to you is document everything.
Get anything people say to you in writing from them (eg people who say they will speak in your support etc) or it means nothing. Time drags on and people change their minds about sticking their neck out or forget details.
Trust nobody. It is amazing how little integrity people have if they feel standing up might be in any way detrimental to themselves.
Have an exit plan and, if you can, think about getting as far away as possible if this shows any hint of turning to an utter shit show like mine.