tips/advice for getting over argument with personal nastiness about you?

Here's a good video that you might find useful

I think it would help you if, instead of telling them you feel like they’re being rude to you, you shut them right down. Don’t let it get past level 1 criticism. Stay very calm. Don’t raise your voice and in an assertive (not aggressive) tone, say something like ‘That is enough. Go and take a moment, and come back when you’re ready to have a professional conversation’. Then turn away and continue with your work. If they don’t like you, that’s fine. But they do have to behave professionally.

Also, if they are saying stuff like that to you, then they clearly aren’t a nice person. And you’ve said that you don’t actually like them, so why do you care that someone who doesn’t know you very well is being spiteful to you because you won’t break confidentiality and tell them what they want to know? They’ve decided to upset you, they’ve looked at all the tools they have in their armoury and they’ve resorted to ‘nobody likes you’. How did you not laugh at that? It’s pathetic! You’re obviously good at your job or they would have insulted that. So take heart in the fact that, of all the things they could come up with, the fact that you won’t break confidentiality is the worst thing they could think of! Laugh at them.

@ADrownedRat you handled the situation brilliantly! You can be proud of the dignity and assertiveness you used, you don't have anything to reproach yourself for.

From what you've said, the person is a bully, simple as, using their position of authority inappropriately, especially after you said numerous times that the matter was confidential and you were not in a position to disclose the information. They levelled numerous accusations on you, and you stood firm. The more they criticised you and the more personal they became, the firmer you held

Id be taking their behaviour to HR especially if they continue to target you. Make a note of times, dates and circumstances and escalate the matter.

OP from what you say you handled the encounter really well. That's not easy to do. You know this co-worker is the one with the attitude problem, and it sounds like you won't be working with her for much longer. So it's just how you stop the conversation replaying on a loop inside your head.
When I have upsetting encounters they stay in my head for ages too. (Also ADHD)
What worked for me: finding an outlet that absorbs all my thoughts for a time. Someone mentioned Zumba. That works, so does an art class, pottery, gardening, anything that takes all your attention in the moment, leaving you with no space to dwell on anything else. Yes when you finish the class or whatever it is the outside world will return, but it always seems a bit further away, a bit smaller, more manageable.
Longer term:
Something like a choir or volunteering at something where you are with others will give you a better sense of yourself as someone worth spending time with. Singing is good for you anyway, but being with people who value you for just being you is also a precious thing. And it sounds like this might be missing from your life. It doesn't matter what the thing is as long as you enjoy your time there.

Avoid the twats.
HR at work and going no contact with on work twats.

I binned someone out of my life because she was an awful two faced cow. She still is but it's other people bearing the brunt of her evil. People let me know as if they want me to start a rebellion against her but she's a psychopath and needs to be avoided.

There's a piece of advice I ready (as I've been a serial ruminator in my time) about considering yourself in the same way as you would your close, dear friend.

When someone says something nasty that affronts, insults and hurts you, think of you protecting your close friend from harm by telling them that they are none of the things the horrible person said about them, they are kind, lovable and as good a friend as they could wish for.

except you're saying that to yourself.

How can the advice already given to you not be worth a try

you're continuing to seek some resolution to the problem which needs you to take the action. None of us on here can change the way other people talk to you, we can only advise you on how to respond internally and externally.

they say habits take around 21 days to become a habit. So you can start by wiping the slate clean, forget what this person said to you because it is only one person's opinion, and from today resolve to take small steps towards shoring up your defences against opinions that don't reflect reality.

the example you gave as being "clever" is just additional manipulation. it certainly isn't clever :

Cutting Comment - I've never had to deal with someone as difficult to work with as you

Response - "Difficult? That's a shame. (Shrug) Funnily enough, I get along just fine with most people, so if it's only you, it's you with the problem not me".

or "well, you would say that wouldn't you". head tilt. A bit of subtle body language is powerful when done sublimely

You've only got to shoot them once and hit the bullseye - because being a nasty bully they'll metaphorically run and hide, or back right off and you can then build your confidence and keep challenging their micro-aggressions one at a time.

generalisations are the easiest to shoot down in flames, because nobody can possibly know what everyone thinks, says or does.

also when someone says something cutting, slow down the conversation, leave a gap, some silence, and just look at them steadily, say nothing, breathe and wait. Then come in with your response, in a quiet voice.

this takes practice but once you've done it to one person, you'll find it a lot easier to stick up for yourself against unpleasant people.

I think CBT distorted thinking training would help you. Partly so you can rationalise how to respond to hurtful comments without getting stuck in them. And partly so you can recognise distorted thinking in someone else's behaviour.

So her comment 'I have never had to work with someone as difficult as you' is typical of the cognitive distortion overgeneralisation. It's when people say 'never' or 'always' or 'everyone' when they mean sometimes, some people etc.

I would place bets that she has said exactly the same to other people.

CBT would teach you to check in with yourself fairly and ask if your behaviour deserved that response. If all you did was say no with boundaries, then you're fine and you realise the issue is how she reacts to staff having reasonable boundaries. If on reflection you realise you have been uncooperative several times when she's needed your input and maybe it would have been reasonable to go the extra mile, then you might realise there was some (but not whole) truth in what she said and decide to apologise or make more effort. But either way, you assess what happened fairly and compassionately, not judgementally or getting sidetracked by other distortions such as 'everyone must hate me' or 'I'm useless at work and should leave' etc

Is it more the fear that the horrible things said about you are true, or the betrayal?

For me, I knew they weren't 'true' ( true for that person, in their head possibly but thats all) but it was the sense of betrayal that would affect me, and the implications for the relationship.

It's human nature to care what others think about us. Whilst the advice on this thread is good, I don't think it's only those with low self esteem who'd find negative comments from others hurtful.

It also depends how close you were/ how well you thought you knew them.

Someone who you thought had your back and cared for you is different to someone on the periphery of your life who you don't know or care about so much

What I’m trying to say is that their comments weigh so heavily with you only because you don’t attach enough weight to yourself, your actions, attitudes, preferences.

I bet when you approach a social gathering when you’ll be encountering new people you are much more focused on whether they’ll like you than on whether you’ll like them.

You need to learn to counter this, and to centre yourself in your own life. As it is, you’re like an object that isn’t securely balanced on its own centre of gravity, so that any passing breeze makes it topple over.

This.....is me. I'm a total nightmare to myself after nasty comments may have surfaced in an argument or heated conversation. I will go over the conversation in my head numerous times and it'll drive me crazy.
Part of the issue for me, is I'm generally really careful what I say to others, even when I'm mad, so I struggle with why others can be so careless with the things they say.
Thing is, if you know you're a good person on the whole, then you have to teach yourself to mentally push mean comments away (definitely not always easy, I know). People will say stuff sometimes; sometimes because it's in the heat of the moment, or maybe they do actually think what they say. Either way, we can't force people to see our good, and not everyone is the same in how they manage a situation.
Perspective is key - even if someone does have a negative view of you, so be it. Nobody is perfect and we all have our faults. When we accept that, things become a little lighter x 🙂

I had a manager at work say some really nasty things to me.

Ironically they were so horrible that I knew they were only saying them to get rid of me.

It actually made me stronger and determined to fight, and when they denied saying it all months later I was even more sure they were the issue, not me.

You may well be the most difficult person they’ve worked with but that doesn’t mean you’re the problem. Maybe you’re the first person that has stood up to them and they’re lashing out because they’re not used to that reaction, maybe they have low emotional intelligence and resort to nasty remarks as they can’t vocalize what they really feel, maybe they get off on being horrible to someone they perceive as weaker than them?

Regular cardio enables your brain on a cognitive level to put stuff in the fuck it bucket. So go to Zumba or something.

Try and take the heat out of what they've said and reflect - do they have a point?

The only thing that’s ever worked for me is addressing the comment to the person at the time. It gives me closure and I can move on from it. Otherwise it live rent-free in my head forever.

Forget the other person or the specifics of what they said. Your focus should be on yourself, building a stronger sense of self, working on your self-esteem. The other person and their behaviour isn’t the issue here — we all encounter unpleasant critical people as we go through life. Your issue is that your sense of self is so weak that you give their opinion too much weight.

I wish I knew. My son Called me a bitch and told me to fuck off a few months ago. And has not spoken to me since. I didn’t do anything wrong ( I really didn’t ) I think he is regretting it now. But even if he came to talk to me I would have a hard time letting it all go as some of the stuff he said and messaged me was just horrible.