To think I’m not the toxic person in this situation?

What is it that makes you think your a narcissist?

She may not have been vulnerable though. She may have made an active choice to be with him. This is an example of something you should never voice to her (even if it is what you believe).

I think you’re spiralling

My advice remains the same as before.

This is her long term DH/Partner/person she loves.

She does not view him the same way you do so persisting along these lines does nothing but alienate yourself from her.

You have to accept she does not view him that way and therefore if you want to have a relationship with her you just simply need to let that go and not mention anything to do with him to her. If she brings him up just ignore or smile and change the subject, for your own sanity.

Many of us do agree with you that you are “the bad guy”

but then you get defensive and say you’re not

We are feeding someone who is drinking. OP, it is very apparent

OP, reflect on how your sister makes you feel.
We don't have to see people whom we don't feel we have a positive relationship with.

Its ok to drop the rope, say nothing and just live our lives without the upset and drama they bring to it, intentionally or not.

Its ok to decide that you don't want to be around the negative emotions they dredge up in you, again, intentionally or not.

Choose you.
Choose peace.

Wishing you well.

Your behaviour is toxic. You're nuturing a two year grudge about an argument you started. I said it on your other thread, you hit (verbally) your sister first and are now playing the victim because she retaliated harder. You reap what you sow and you sowed spite so got it back in droves.

You're the problem.

Broadly I would say that if you are worried you are a narcissist you are unlikely to be one

But when we agree with you that you probably are… well, hell hath no fury!!

Maybe she isn’t sorry and that’s why she hasn’t said she is. Perhaps she said that she didn’t want to talk about it ever was her way of being able to move past what you said, but she doesn’t feel regretful about what she said in response.

I think you have to decide if you want to let this go and continue to have a relationship or not let it go and not have a relationship with her.

And frankly, it doesn’t sound like you can let what happened go.

Then I think you should have some therapy and thrash things out there, where the only object is for you to understand yourself and formulate a way of moving forward with your family relationships. No therapist can reassure you that you're not 'as awful as you worry that you are', but they'd be up for teasing out why this is the point you seem to keep coming back to, as if you wish some umpire or referee could come in and declare authoritatively that either they're 'toxic' or you're 'awful'. Is the reason you want to be assured that they're the bad guys because you're worried that, if they're not, you're the bad guy?

Of course you're only giving your side of the story -- that is the only one you can give. But presumably you're aware of the possibility of another side, where your sister might say 'My sister got angry about my husband dropping the ball on the sale of our flat, I defended him and she responded with a barrage of drunk criticism so spiteful and vicious that even after she apologised, I couldn't bring myself to forgive her for months. Now she wants to talk it all through, but I can't bear to think about any of it, as she clearly hates and despises my husband, and there's no getting past that'?

Agree and is gaslighting not a sustained campaign to basically fuck with someone's mind? Not an innocuous, one off and truthful comment!

Read some of your OP back to yourself.

I apologized repeatedly for my words. She thinks she apologized for hers, but it was very much ‘You made me say it’. She’s never accepted my apologies in so many words. ‘I’m sorry’ was met by silence.

So she believes she has apologised but that you started it and that she wouldn’t have said what she did without provocation from you. There’s nothing wrong with that. How else is she supposed to accept your apology except by moving on and not talking about the argument again? You sound like you want more from her than you can fairly expect.

I’ve since heard stories about my BiL from my daughters and DiL that make me think he’s a narcissist or at least a genuine creep.

How is this related to the previous paragraph about your sisters apology? It has nothing to do with your relationship with your sister. You don’t have to like your BIL, but you have to accept that your sister does. Or, you can choose to stay away from both of them.

My sister was so horrible and unforgiving and seems to have forgotten that now.

But you were horrible too. Why did you get in contact and apologise if you don’t want to forget about it? Again, you seem to be expecting more than you deserve