I know this thread is a little old... hope you don't mind me adding to it.
I used to be embarrassed that someone would ask about my cuts and or scars. I would lie and say "oh I was hiking through some brush that had a lot of thorns and got all scratched up." Or "I got attacked by the cat."

But then one day I just decided that I was going to tell my parent, and all my friends and their parents. And I did! I cried a lot and agonized about actually telling them.. how would I do it? In person? By letter? One on one? Ultimately I chose different ways for each person. In a way the agonizing and then the release of actually telling them replaced some of the SI for a little while.

At first it was super awkward with some people, and my mom cried and was really worried about me (she thought I was suicidal, but I explained to her that i wasn't, and my therapist explained it to her more, and that helped her calm down).

For a little while I felt kinda angry about telling because that made the people who cared about me the most actually step in and Help me. And I didn't want that! I wanted to SI and just have it out in the open. I didn't want my mom or my best friends asking me if I was able to go that day without SI. But eventually I started to realize they weren't judging me they were just trying to help me. And that help wasn't a bad thing.

I started to realize it wasn't anything to be ashamed of, that it was just something that I had been using to cope, and that others were helping me see their possibly could be better ways to cope. Like expressing my emotions instead of hiding them. And taking my medications regularly.

I used various methods to stop self harming such as drawing with red markers.
I have gone many years now without cutting and most of my scars are completely gone now (olive oil massaged gently on the scars and honey wraps really helped soften and flatten them).

But right after i had stopped, when they were still very noticeable, I decided that if anyone new asked about them i was just going to be very mater of fact about it. I would explain that I had dealt with a lot of depression and had been in some extremly abusive situations that caused me to try to find a way to have some control in my life, and that often people in that kind of situation might turn to doing things like self injury as it gives a feeling of relief from the emotional pain by focusing on physical pain. I would explain that it was not an attempt to cause serious or life threatening injury, but simply a means of trying to cope with emotional pain in a way that brought that pain to the outside of my body where I could bandage and take care of the pain and watch it heal.

I was really surprised by how many people understood this explanation! It was of course often followed with "But you have stopped doing it now, right?" And I would honestly tell them how long it had been since I last did it. And that I was continuing to receive help to learn how to deal with it all, and that I was confident that eventually I would be able to do it less often or perhaps not at all, as I continued to form other ways to cope. And that usually was the end of the conversation, we would go on with whatever we had been doing.

I was even completely open with children about it. I would simplify the explanation. For some kids I would simply say "those are called scars, that is what happens when you get a cut and it gets better, it heals up but the skin just looks a little different where the cut was. Tat satisfied a lot of kids.

Other kids were the type that would push for more information, so i would say "Sometimes I have been really sad and really afraid but I didn't have anyone to help me feel better or to keep me safe. So my brain made me think that maybe I would feel better if I had cuts on myself and then I could make those cuts feel better. But now I know that isn't really a very good way to feel better. And I have learned that there are people who can help me feel better and then I don't feel like having those cuts on my arms any more." Before they could ask another quuestion i would immediately say "Can you think of any people who would be good to ask for help if you or one of your friends feel sad or afraid?" They would answer and I would say "That's a really great choice!" Or maybe I would suggest some other ideas, like a teacher at school or the nurse, Or a doctor. If they were a child I knew, friends or relatives kids, I would add that I would always be happy to listen if they had anything they wanted to talk about.

This put them at ease and took their mind off the scars.

I don't know if you guys would find this approach a beneficial way to deal with SI or not, but I just thought I would share this,

All the best to everyone ~ hold on and know you are not alone.