It's absolutely understandable to feel that way, but the fact that you're even resitting is amazing. I know it will be hard to see your friends going off to university and you will feel sad for a while, but try and motivate yourself- do you have an ideal course? Or a dream university? See this year as a year to excel and set your sights firmly on the place you want to be, treat yourself to new stationary as such and if you haven't already - get yourself a job. At the end of this year you're going to have a reservoir of savings, and you're going to get that offer and meet it! This is a new year, fresh start, make goals and see this time as an opportunity!!
*Hugs* It WILL get better!!