Jemma | Gabriel.
That's a bit rude of him to assume you were a waste of time because your ability was more subtle than others he might have been studying. Putting people back together is definitely not a simple task, especially if you're not familiar with the workings of the human body. I don't know if your ability would allow you to know that or not.
Addiction is a disease and not one that is easy to treat. Even if you are aware you suffer from it and want to try and get help it is a long battle. So few people realise that an addiction is something you have to battle for the rest of your life.
So you thought your ability was supposed to work one way but it was actually different from how you thought. It sounds to me like you know what you did in the past was wrong and that you no longer do those things. Someone close to me always said people deserved second chances and it sounds as if you got yours, not everyone does.