I just had to report something to the police that will probably end a very close friendship of mine, but it was something that was totally not okay and I had to do it. But I still feel like a piece of shit for it. Have you ever felt like this and how did you get through it?
I think the big thing is sometimes giving it time. In hindsight the other person may agree that you did the right thing.
Ultimately if you can justify it to yourself based off morals that make sense, time will heal the wound.
All the best.