…To Ghost Employer

You could try a third option.

Take copies of every snarky and bullying communication (probably paperbased is the best way to avoid accusations of breaching security through emailing things to yourself)
Get signed off sick.
Leave the means for her to continue to contact you so that she further evidences her behaviour.
Submit a grievance, ensuring that she still has the means to further support your case by contacting you.
If it's clear on investigation that they're in danger of a constructive dismissal case, they may be open to negotiating a settlement and agreed reference.
Leave.

If you don't turn up they'll probably send the police out for a welfare check

You'll need your P45.

You need to end your contract properly to get that.

OK, here’s what I did in similar situation.

I resigned (you have to really or it can cause tax issues) but told HR I would not agree to any meetings or phone calls with bully micromanaging arsehole. I would communicate with them only in writing/email.

He was INCANDESCENT which gave me great satisfaction.

Surely you will need your employer for a reference? Even if not for this job, maybe another. It’s not worth risking that.

You can hand your notice in, you can even be explicit as to why you are leaving, and then do only what you are contracted to do and ride it out. And all the time you are working your notice, you will feel such relief and happiness that you are on your way out!

You have coped this long, so for the sake of no repercussions, hand in your notice formally and work it. Or hand in notice and see if you can get signed off.

You coped with it all this time, don't lose a final wage and any pension/benefits for the sake of a few more weeks. Then you can stick your finger up and move on

You've managed 6 years, just manage 1-3 months more and they won't ever be able to say you breached your contract in references.

Then you never have to see them again!

You really do have to resign formally, as it will create hassle for you if you don't . Whether you work your notice, cover it by sick leave or whatever is up to you.

You can do that of course.

You simply have to be willing to accept any consequences of breaking your contract, up to and including legal action against you.

Realistically they probably won't bother unless you walking away causes them massive financial loss.

Morally perhaps you're right, but legally and for tax and pension etc. etc. you'll obviously have to resign formally! If you're employed in two places that'll create a tax etc. mess and you might be in breach of your employment contract.

Just hand your notice in and then leave. Its not worth the hassle of her trying to hurt you.

Can you just hand your notice in, and a sick note for the notice period? Get signed off with stress. If you just disappear how will they know you’ve left and pay final salary etc.

She sounds like a nightmare. Can you take some time to document everything and submit it to HR as a formal complaint/ grievance to cover yourself and then send in your resignation and cover your notice period with sick leave. As galling as it is, if you cover yourself and follow correct process and stick to your notice period, then they can't claim you have done anything wrong.

Just get on with it. And mention your brilliant new job as much as possible, to her.

If it's affecting your mental health could you get signed off sick for the period of your notice? I wouldn't just leave as I would be too worried about repercussions. At least if you work your notice, after that you can be sure never to have nothing to do with them again.

How has that gone on for 6 years without you telling anyone else? Going above her? Going to HR?

She sounds like a complete dick and the type to really push for a breach of contract on your part if you don't work your notice. Without any complaints from you in 6 years, HR would probably back her because they don't know anything.

Tread carefully here as this may backfire.

have you raised the issue with the HR?