In marriage therapy terms, we see contempt as a moral superiority over one's partner. Basically, if you're contemptuous, you see yourself as better than your partner and as having the 'moral' high ground…
Think of a time when you felt attacked. Maybe it was by your partner, maybe it was by a stranger, family, your boss or coworker, or a friend - it doesn't really matter who did it. The point is this. Take yourself back to that time and recall what it felt like in that moment.