What's the most difficult moral dilemma you've ever faced?

I dont think i have ever been faced with a moral dilemma. Normally my decisions are made Instantly, i dont always know whats right to do or not to do. I Just act, if i feel its right then its justified in my head that its ok, and if its wrong i learn the lesson not to do it again. Sometimes after i do something i reflect on it and think of other ways that i could have acted.