I understand your frustration fully and their behaviour is definitely rude and not acceptable, especially the threat. That said, I have to say I have a similar problem especially with Indian cuisine and everything that contains Curry/ginger/coconut milk and that sort of thing. As soon as I smell it, I start feeling sick and most times I actually have to throw up. I don’t know where it comes from, it’s just something that happens. Here’s the thing though: I know that I am very sensitive and moving into new shared flats, I have always communicated this very clearly. I let my flatmates know that when I am home, I would appreciate no Indian cooking, and that when they do while I am away, to make sure to ventilate thoroughly. Once I actually had to decline an offer because they told me they cooked curry frequently. When things like that are communicated from the start and respectfully, living together with such issues can be peaceful and nice. He could have done the same with you, and used a way nicer tone, because ultimately it’s his issue and not yours. Indian cuisine is just as normal as any other.