Will I ever be able to shut off all of the things going on in my head?

No. But you’ll be able to control them and learn to turn them into Positive Attitude. They’ll become your power. To do that, one has to be able to understand what matter the most in life. And in life, the one thing that cannot be changed and is irrelevant to think about is Past. Do not dwell in the past and one day the thoughts will be at peace. Changing them from negatives to positive will include changing your lifestyle too. Change in your habits and a change in your friend circle and people you hang out with. Thus, it will require you to move on from things and people in life and find better people with empathy to give.