Are these complex mathematics problems/ equation will going to have a real life use in the future?
Yes, of course. If you're an engineer, definitely you're going to use all sorts of formulas to solve those complex equations.
School makes student depressed, suicidal, feel stupid, wanna die, hate life, sick, nervous. Is this what school for? Or maybe I am not just realizing it.
From my experience, it is better that I had experienced all those emotions in college; it made me emotionally and physically stronger as an individual.
At school, we're going to learn all the things that our parents can't teach. Maybe one day, you're going to thank some of your teachers for all the knowledge they had imparted on you. So, school prepares us in "the real world".