First off, don't have the mindset that you "can't do it." I went into Organic dreading it the first day and it turned out to be my favorite class in all of undergrad. The thing with Organic is that it IS a challenge, whether the material is a challenge or just the managing of time because Organic takes more studying than any of your other science classes, ESPECIALLY Organic 2!!!
I think you should just study REALLY hard for this next exam and have the mindset "if I can do this, I can do medical school"...because I firmly believe that you don't learn how to actually study until you hit Organic! Once you ace Organic, every other class the next few years will be a BREEZE!! Not because the material isn't difficult in other classes, but because you will really know how to study after organic!
If this gives you ANY encouragement, I got a 69 on my first Organic 2 exam after making 100's on ALL my organic 1 exams two semesters before. However, I had changed schools, changed teachers, and changed textbooks in between org 1 and org2 and I had a lot of "catching up" to do because of this transition. I cried for about 2 weeks over this grade and I, like you, couldn't decide if a W or an F was worse! I didn't withdrawal and at the end of the semester I had the highest grade in a class of 200. Anyways, point being that you can REALLY do this if you REALLY want to!! Make organic your first priority as far as classes are concerned. A med school is going to look at your A in Organic more than your A in underwater basketweaving! 😉