Meh, your biggest enemy atm is you loosing your nerve. Just calmly deny and point out that its an unfounded accusation. She has nothing.
The more she shrieks the more innocent you look.
Just keep your public nose clean and stay ice cold.
DO NOT INITIATE ANY ACTION AGAINST HER.
No one will be fooled if there is a white pillowcase with eye holes in her desk draw.
This doesn’t mean that you cant be booted, it just means that she has to manufacture things to get you booted and if she is determined to do that there really is little you can do about it.
Start looking for a better job if you like.
Get better acquaintances.
If she continues you could easily bring a case for harassment to HR, but only when its serious and public enough. A little petty perhaps but that’s the environment you’re in, anon.
Stay calm, relaxed and don’t get carried away with what you 'think' she knows.
Don’t try to plant anything or force the issue, just keep your head down.
When/if it escalates to the point that it becomes a HR issue then MAKE IT A HR ISSUE. But politely, don’t swear or demand.
Keep all paperwork, emails etc...
And finally, if you do get sacked they leave themselves open to a case of constructive dismissal or similar. If you cant afford to pursue that (just like most of us) then leave with excruciating politeness. Then burn down the offices/the cunts house 12-18 months later