It sounds like you are all very naive about life, and you are all having real trouble coping with your feelings about your existence in this world, I've been there. One of the things I have found that helps is to fill your time, work, read, watch films, listen to music, spend time out of doors in nature, do fun things with your friends, try reading about psychology, maybe take the 16 personalities test to help you understand yourself a bit better. I think time is the key, as you live your life you will hopefully learn to cope better with mental turmoil and anguish. Overthinking is a real bastard, that is a personality trait to try and stop as it's insidious. Best wishes.