A secret I've never told anyone and why

A secret I have never told anyone is that from the age of 13 to 19 I would self harm. For the first 2 years I would self harm on my arm, thighs, and hip area. I would always have a sweater, flannel, or long sleeve on and I was never questioned by anyone. I live in southern California and it gets hot here and by the time I was around 15 I stopped cutting my arm and only would self harm around my thighs, hip area and upper arm area because I was able to hide it because I would always use t-shirts. I would occasionally wear shorts and skirts but only with leggings or thigh high socks. I never told anyone about myself harming and if they did notice it I was never asked about it. The reason I never told anyone is because I was scared of what they would think of me even if they were my friends. I know for sure that my parents would think I was crazy. Currently I am 21 and I have been clean for 2 years (almost 3). I still wear outfits that cover up the scars but I plan on getting a meaningful tattoo soon to cover up some of the scars and when I do I will come clean to my family and friends.