Your actions were not the best, but they also probably saved his life. I can't say much more than that, because in your place, I would have ripped that blonde Death Eater into shreds and made sure he lived long enough to see me do it. Taking H away was what concerned me the most... but it's done now. It was your first raid, your first kill, and a high-emotion situation. I shouldn't have said that in the owls... you have growing up to do, but you're not immature.
You're only 18. A lot of life ahead of you, a lot of people yet to meet. Keep him as a friend. It's not worth clinging to a false hope, especially when you're making yourself more and more pained doing it.