Congratulations Big Time!
Let me tell you something and also try and keep it brief. Your entire life will be about stressful situations/periods like these. You will always wonder how you will get through, but you will. It is about growing up and making your way.
I often look back and wonder how I have done some of the amazing things that I have. You just pull it together and get through. Trust me!
I was at a very large, competitive school and went the pre-med route and let me tell you it was taxing. There is nothing harder than majoring in the sciences and staying put with top grades. You compete against some of the most talented/intelligent students at a university. There are countless labs and very difficult exams and getting a B or C just takes your chances away for future opportunities. You just focus and you get through.
I have so many regrets from college in that I did not spend more time with my friends and going to socials etc. You get one chance to do this and if you pass it by you will never see it again. Please try and take a deep breath and focus on your goal and find some kind of balance that works for you. You can do well in your nursing while enjoying your sorority and all it has to offer you. You just need to look within and find the balance that works best for you. Trust yourself.
I wish you all the best!