I masturbated in middle school in the hallway after detention class. This was 20 years ago...
Why did you masturbate in public when you were in middle school?
At that time I got endless punishments for my grades because of my lack of interest in studies. This made me depressed. I heard that masturbation relieves depression
It sounds like you feel guilty for your actions from when you were a child. Puberty can be a confusing age for many people, don't put too much pressure on yourself for what you did in middle school.
I don't feel guilty about it at all. It pleases me to remember it.
Well, that's pretty gross. Masturbating in public is not only offensive, but also illegal. If you did that as an adult you would probably be on the sex offender's registry, so don't repeat your actions.