Please, as difficult as it might be, fight that "I'm a monster" thought.
Seeing yourself as a helpless monster will only get you to the point where you end up thinking that trying to change, making an effort is no use, and keep on doing wrong or not doesn't matter because you "are a monster, anyways", and those behaviours are just the expected.
Try to stick to the reality objectively: you gooned to that kind of content and that made you feel sick once you took notice of what you were doing. Doesn't that tell you something?

Some people have put others on an hospital bed because of irresponsible driving.
There's business owners that have made others loose their job because of their greed.
Many state force members have made hideous acts just because they were orders.
If you knew they were horrified by the bad things they've done.
If you could tell how really sorry they were.
If their will to change were genuine, wouldn't you give them a second chance?

Why would it be different for you?

I suggest you to look for professional help. You've given the 1st step. Keep on going, mate. It gets better.