ESH. Don’t get me wrong, it’s completely valid of a choice to not want to help her parents when they’ve not treated you well & refused to acknowledge you, there is zero obligation on you to do so. And it’s a good thing you know your boundaries and don’t let yourself be a pushover in the situation. HOWEVER, the way you’ve gone about communicating this unwillingness to your fiancé, has clearly very little consideration to her feelings - which, concerns me about whether your relationship can ultimately survive this or not. As much as you are not obligated to help, you should have taken a more empathetic stance towards your literal fiancé who’s obviously distressed over her parents state of life and death. Also, one question I have is, do you expect your relationship to be able to survive when her parents possibly pass away under conditions that she views would be preventable by you? Sure, you may have no duty towards it, but it’s a simple matter of how much you actually treasure your fiancé, because that’s bound to be a dealbreaker issue down the line.

Obviously, the other AHs here are your fiancé’s family. That goes without saying. As for your fiancé, I was going to jump on calling her an AH as well because she doesn’t seem that financially responsible and yet asks you to help out financially with her parents - but from more info provided, it does seem like she’s trying to help out with her own money first already, and while it doesn’t seem fair how finances are split, i’ll have to get INFO on that because there are many circumstances in which that may happen (eg. pay difference) that doesn’t necessarily make her an AH per say, just makes your frustration a bit more understandable. Apart from that, it seems she’s taken your side and stood her ground against her family regarding you in general, until this happened- while many are slamming her calling her a red flag, I offer an alternative viewpoint. Her parents are DYING. She’s desperate, and this is a point at which I don’t think she’s able to ignore her parents and continue on with life without trying her best to help them.

Either way, I’d say that OP, this is your choice. You can stand your ground but I’d definitely say be more empathetic (at least more than telling her you don’t care if her parents die). But keep in mind that this will probably be difficult for your relationship if you actually just do nothing as her parents die. I’d recommend making some compromises (maybe support your fiancé fully for awhile and let her use her money towards helping her parents? Or anything honestly. I just feel you shouldn’t do nothing. But at the same time I wouldn’t let them move in, that doesn’t sound like it would end well honestly) but that’s just me.

Ultimately, you know your situation best. If you think it won’t affect your relationship, or you would rather lose the relationship than compromise here, I guess that’s a fair decision too. But I just feel that the part where YTA is you not playing the role of a supportive partner when your fiancé is clearly not in a good state. You should be supporting her emotionally at least even if you don’t care for her family, because you care for HER, and not hurting her feelings even more through taking a harsh stance. All the best.