Since you are 20, this is a college class, correct? Drop that mofo, immediately. It's before the drop date for most universities, so you have time. If you need the class this semester, try to see if you can enroll for an eight week course with another teacher. Imo, unless he said what he said in a threatening way or made some physical advance or otherwise intentionally violated your safety, I don't necessarily see anything wrong with what he did. You are both adults. However, it is incredibly understandable that you are uncomfortable with it, and you have enough stress to deal with in college. If you drop the class, he should get the message that you aren't interested and neither will have to deal with the other after the fact. In that sense, it is best for both parties. If he continues to bother you, that is stalking and you should contact the authorities.
If, like we all have done at some point in our lives, you have put a different age than your own on your profile, and are in high school or middle school, see Mahlua's advice.