Shame can be a powerful emotion. It is hard to shake and can lower your self esteem. It is very difficult to talk about self harm, especially with a group of people that may judge you.

In the future you can say you don't want to talk about it, that it is a sensitive subject. It isn't a lie and hopefully they will drop it. You can lie, but it becomes difficult to keep track of who you told what to.

I have a mot of scars on my legs. No one has ever seen them thankfully except doctors and medical people.

Try not to be ashamed of yourself. Self harm means you were really struggling and did not know how to cope. Most people don't know what that type of pain feels like. They can't fathom how self harm would have any benifiet. I don't think telling the masses about it will make you feel any better, but when you get people that you trust and are close to you, maybe you can explain to them. Tell them how much stuff you were going thru and that you didn't know how to deal with it. That you self harmed and it made the bad feeling numbed or what ever it does for you. It does different things for different people.