I felt similarly after I left undergrad. First and foremost, I would recommend going to a doctor and getting some antidepressants. I was extremely skeptical about going on them because I feel like we're over medicated in the West and very quick to diagnose everything, but once I started taking them I felt noticeably better. The depression and negative / violent thoughts do not go away with medication on their own, but it takes the edge off, and, in my experience, they kind of just roll over you rather than becoming fixations. If you can afford it / have coverage, go see a psychologist as well. They can help you develop very effective strategies for dealing with depression and negative thoughts.

If you hate your job so much, you should start to develop a strategy to find one you do like. Also, you're young and don't have kids or anything like that, so I find it hard to believe that you don't have time to go to the gym for an hour and a half after work a few nights a week. I, too, have a full time job and I go every day. One days when if feel too tired or busy or whatever I don't go, and it's no big deal, but you should be able to go sometimes, even if its just on the weekends.

And also, where is it that you live and that you can't you move out of your parent's house if you make decent money? Even if you can't afford to live alone - which many, many young people can't, even those with excellent jobs - I'm sure you could find roommates your age to live with, which would reduce your living costs. I did it for three years before I moved into a better job and was able to afford my own place.

Life is what you make it. I now things are hard for young people today, but if you have a job with benefits you're better off than most. I know that doesn't change how you feel right now, but I believe you can change things in your life for the better if you try.