I have made a lot of mistakes in my life and have plenty to apologise for. The thing I am most sorry for is not speaking up to one of the people I cared for, and to stop them from hurting another person I cared for.
I have never apologised to my friend for not speaking up for them. I don’t want to open old wounds that they may have moved on from. I still wanted to get it off my chest, and maybe it will make others consider what they are most sorry for and address it in some way, even if it just means writing it down.