Hm, well, that first question is, unfortunately, something I can't answer for you. Everyone has different tolerance. Everyone has a different capacity to handle someone else emotionally hurting them before they give up on them. But, do know that it's not your fault if you do want to give up on it. You're not alone here, and if you truly can't handle it anymore, you have people here to support you if there are ties you want to cut off.

However, if you want to make progress with that person, as I said, arguments are likely to keep going the same way if you intend to let them be on his... their terms. Which is to say... mmh... Let's say I claim I know water is blue. You know, without a shadow of a doubt, that water is clear, actually. Environments and reflections are often what makes water "change" color. You do everything to show me I'm wrong - you explain the chemical bonds, you even show me a bottle of water, and anything else that is irrefutable proof that water is clear.

I still say water is blue.

This is what I mean when I say this is something that they've accepted as their reality. It's not possible for them to skew their perceptions because you're trying to argue against them on it. It's better to not challenge their views, but talk about what's upsetting you instead.

You shouldn't talk about the water with me at all. The water doesn't matter. You have to talk about how you feel about the fact I'm not trying to see things from your point of view at all, and simply shutting down anything you try to tell me.

Does that make sense?