Are emotions just illusions?

It's a difficult question to answer. I would say they're not illusions.

We're not directly "taught" how to feel about things, we're conditioned to. We learn whether or not something is good/bad/dangerous/etc as we grow up, and our emotions react accordingly. You can be taught why you feel this or that, but you can't be taught HOW to feel this or that, as feelings are chemicals being triggered in your brain and that's not exactly something you can do on command.

Emotions are the language of the heart