I need advice

Everytime I see or talk to my friend all I can think about is how he cut himself infront of me. It was a very scary experience because there was a lot of blood and I had to be responsible for bandaging up his arm but I feel like I should have gotten over it by now. I just feel like I can't though. I have been struggling with sh too and I know how addictive it can be but I feel like doing it infront of someone who he knew struggled with it too was kinda rude. I don't know though. I don't know how to forget what happened either. Does anyone have any advice for me on how to forget about this incident?