My older sister is leaving to study abroad in Spain?
You should let her go. Studying abroad in Spain sounds really fun. It will be a good learning experience for your sister, you should be happy for her. Any learning period less than 3 years is considered to be a short amount of time for studying abroad in a different country. Plus, Spain is a good country with lots of good food. You can always contact her by phone, skype, etc. After she comes back, then you can always be with her.
Wish Sis well - tell her have a wonderful time. You aren't going anywhere, and it's time to grow up yourself. Don't hold Sis back, don't guilt-trip her. You have to let go & build your own life now.
You can keep in touch with her - social media, WhatsApp etc
Can you email her while she’s gone? Will she have her phone? (Have your parents check with your cell provider about texting your sister while she’s gone, sometimes it’s really expensive and sometimes you can add international texting and data for not that much) Can you face time or Skype? Ask her to send you lots of postcards they’re fun to get in the mail and a cool keepsake.
Skype, text, Facetime, e-mail, other social media. All those options weren't available to 13 year olds whose big sisters went to study in Spain 20 years ago, so you're fortunate.
Really nothing to suggest other than Skype or FaceTime.