I Got a "D" in AP Calculus 1st Semester... Continue or drop?

I’m a Senior, and 1st semester has just finished. I ended up with a D in my AP Calculus class, and I’m worrying that it will affect my chances of being accepted tremendously. I was wondering if I should try to continue on 2nd semester by staying in the class, hoping to improve my grade, or if I should switch out? 2nd semester has started and I’m already struggling to keep up with homework, and I really don’t see myself improving all that much.

Some background information:
3.91 GPA end of my Junior year
3.83 GPA after 1st semester of Senior year
1590 SAT score (Unfortunately)

Rigor:
Freshman year - Honors Freshman Language, Honors World Studies, Honors Integrated Science, Geometry, Spanish 1
Sophomore Year - AP World History, Honors World Literature, Algebra 2, Honors Biology, Spanish 2
Junior Year - AP English language, AP U.S. History, Pre-Calculus, Chemistry, Spanish 3, Leadership
Senior Year - AP Government, AP Physics, AP Calculus, AP English Literature, Leadership

ASB Treasurer Senior year
Junior Class Public Relations officer
National Honor Society Club member Junior and Senior Year
Certificate of Recognition
Distinguished Scholar (3.75 GPA and above freshman through junior year)