You can have chocolate without out it being self-injurious, if you are careful.
I cheat once a week. I don't feel guilty, but I also don't overdo it, and I am careful. You have to determine what your limits are and stay within them.
If someone at work is having cake, I would take insulin and take one or two bites. Then I wait about a half hour to an hour to have more. It takes me about 2 hours to eat a piece of cake b/c I coordinate it with my insulin peaking. That keeps my BG quite flatlined.
I also sometimes take a longer walk at lunch so I can eat more carbs. About 30 min of walking gives me about an extra 15 carbs I can have without needing extra insulin. They also have to be fast acting carbs, so I get to "cheat" whenever I feel like doing extra exercize.
Remember, though, insulin is a growth hormone that causes you to store fat. You should cheat infrequently and in a way that you are not having to take too much extra insulin, or you might get FAT. = )