I'm terrified that I caused my friend to get into it too

I started hurting myself nearly 7 years ago. The very first person I ever told about it, I didn't even mean for him to find out. He was one of my two best friends in school, and he happened to see the injuries and he asked what happened. At first I lied about it, but a few days later I decided to just tell the truth. When I did, he immediately became fascinated, asking how I did it and if it felt good or if it helped me. I told him he shouldn't get into it and that I regret that I ever started. We stopped being friends months later for unrelated reasons but part of me always was worried he did start hurting himself afterward. Both of us came from traumatic backgrounds, and we both later found out our other best friend was also depressed and self harming.

We reconnected recently after 5 years no contact, and I found out not only does he remember me opening up to him about it, but that he later did start hurting himself as well. I now feel so much shame for ever telling him I did it and now I can't help but think that if I never told him what I did, he never would have started doing it. I feel like a monster.