1.skiing. there is no way that this should make you feel sad. like the other guys said, don't worry about progression.
2. uncertainty of the future can be scary, but a couple years later...you will look back and see how small of a thing high school really is.
3. friends will come and go. most people I know have only kept a few good friends from high school.
4. failure with women...that is supposed to happen in high school. that should be the least of your concerns. honestly, you can't force love...it just happens.
Focus on the good in life. Be happy that you have your health (hopefully) and family. Spend some time with grandparents. Try going for peaceful walks and just appreciate the world around you. Think about how big the world is and the HUGE problems that some people face. It is hard to put yourself in someone else's place on the other side of the world...but BILLIONS of people before you have felt depressed at some point. You'll make it :)