"I feel nauseated."
Translation:Jag mår illa.
I noticed that using adjectives vs adverbs varies across languages. So maybe the idea is to teach this particular case, where English uses an adjective Swedish uses an adverb. For example in Polish is the same as in Swedish. Another example Maten smakar gott and The food tastes good (not well).
England here. In my experience 'to feel nauseated' means to feel emotionally affected by some terrible, shocking behaviour or incident and you could also say 'I felt sickened'. To actually be feeling physically ill when you might feel like vomitting is 'to feel nauseous' or 'to feel sick'. If you were describing how you felt the day before you would say 'I felt nauseous' or 'I felt sick'.
Only there is this big debate about how "nauseous" actually means "to cause nausea in someone else" that DL probably was trying to avoid. A lot of people still say they're "feeling nauseous" when they feel sick to their stomachs but there's always the underlying possibility that someone may pounce on you for doing so.