How can I tell my parents about self harm without them freaking out? I went a little outside my margins and the cuts can’t be hidden

If you want to tell them, just tell them. There's no avoiding them freaking out. They're parents, it's what they do, they freak out on everything. But it's because they're worried about you and would want to help in any way they could. They'd want to help you, and I hope you'll let them. It's they're way of saying that you're not gonna be alone with this anymore, they're gonna be there now. Telling them ain't gonna be easy, and scary, but when you built up the courage, just come out and say it. They'll freak out, yes, but they'll also help.

I know it's hard to just tell them, sometimes it's easier just to write down what's going on and give them that instead of saying it out loud.

try telling them something like: hi (parent/s) I have been struggling and started doing something called self harm. I need support with this and don't want you to freak out . OR you could send them/give them an article or leaflet on self harm and say that I have been using this to cope and need help with this. The last thing you could do is have a therapist tell them about self harm. As for freaking out, tell them that you have been struggling and need their support. I hope this helps.