Should I repeat it? Or is this sufficient? Only class I've ever done poorly in. And It was while taking 16 other units of science classes. :(

C or higher required for most programs. you'll probably have to retake. Contact the schools though and
See what they say

The "minus" is the real bummer here. All of the schools I have looked into require a C at the minimum.

Have you contacted your professor to see if he/she would be willing to bump you up to a C under any circumstance? I think that might be a good first step before repeating an entire semester.