Ironic vs. Coincidental
Nauseous means causing nausea; nauseated means experiencing nausea.
So, if you say "I feel nauseous" what you're actually telling everyone is that you make them sick!
Now what you know the differences in these words, use them correctly when you are speaking, and especially when you are writing. It will show that you have a much firmer grip on the English language than many people around you...
Which should not make you nauseated at all!