I had this done to me and I stuck it out, hoping she would see I wasn't a threat and go back to normal.
She didn't. She literally made me miserable. She would criticise me in front of junior staff, she had one staff member she liked and it was like mean girls, nasty looks, giggling when I went past, whispering. It was like being back at school.
The icing on the cake was when one of that staff thought they were sticking up for me when she slagged me off to him, saying I was good at my job and always helped newer or less experienced staff, he then said he was surprised I didn't apply for the job she was doing when it became available.
She found an excuse to sack me. I went off sick, probably down to the stress she put me under, and without my knowledge a directive came down that staff absent at a certain time of year (New Year's/Christmas) would need a GP note or would be seen as bunking off.
So when I was off just after this was put to staff, I had no idea, and went with the company's policy of sick note after a certain amount of days.
She sacked me for gross misconduct for being absent without permission. I tried to fight it but it was in 2008, just as the financial crash happened and effected my industry hugely. I struggled to find work as I had no reference as they refused to give one. She also sacked 3 others for stupid reasons who she saw as "on my side" not hers.
I then found out I was pregnant with DS so had a break anyway. The business itself went under six months after she sacked me. I can't lie, I thought it was karma.
So get out whilst it's on your terms and a reference is available. Or speak to a union if you can.