I think the two are mostly unrelated, feeling sad/crying and masturbation. I also am sensing guilt, but you don't have anything to feel guilty about. Everyone does it, and your friends are lying to you if they say they don't. Sexual desire can be related to testosterone. A healthy teenager has plenty of that. Testosterone also contibutes to aggression. I attribute this to evolution, a way for our bodies to push us to reproduce. Around 16 both men and women go through a lot of changed and hormones are a big part of that. Masturbation is only a problem if it is hampering your life. If it is like 15 times a day then you may want to go to the doctor and make sure nothing is going on that could drive your sex drive up. I think your feeling guilty about it and projecting those feelings onto the actions of other people.
I think your feeling sad because you are missing a sense of belonging. Having a good family life/interaction, friends and partners provides this dynamic. I don't know what is going on in your life, but I sense you lack support from those around you. I grew up in a crappy family, my resolution was to get through school and get away from the drug addicts and alcoholics and have people in my life that are positive influences. I hope this helps.