I had a long cut from the bottom of my palm to the crook of my elbow. It looked more like a really bad scratch though from the fresh swelling and my mum saw it even though I turned my hand inwards. She was convinced I was in a fight and yanked up the sleeve of my uniform to reveal... all the other cuts. I weaseled my way out of that by saying the long cut was inflicted by one of the school cats and the others were because my arm was itchy and I scratched too hard. I don't think she believes me but she let it go, though she did discover my blades thrice (because she snoops in my bag).
Yeah I was ABSOLUTELY terrified. I was perfectly cool with my T seeing them but not my family. My mum is one of the biggest reasons why I SH and since I was a child I had learnt to build up tough walls and never let her see me vulnerable.