Start by getting other hobbies like fitness, plan in daily time to study and study at a friend's house, in the library or under your parents' nose.
For me it's also the only reason that I managed to study for these exams, my gf slept over all month and we studied together. Last year I played 24/7 and didn't even go to any of my exams in january. Did only one single exam in june and one in tuhe third period. Shit was not fun, but like you I couldn't stop even though I hated myself for being so stupid.
Also go ask for help at the psych of your school/university. It can only help.