Desperately Wanting Step Dad

My mum and stepdad have been together for ages, but I've always had the hots for him since I knew what it meant to have the hots for someone. He's a good looking guy who still plays football so is still in shape and his cologne makes me weak at the knees. Every time I masturbate I think of him and watching him and my mum kiss on the couch is torture because I want him to be kissing me instead! It's lead to a proper rift between mum and me because I get so jealous of her when she's being a bitch to him for having a beer after work.

I've been debating making a move on him for ages but I've always chickened out. Once I got as far as the bathroom door in just my robe when he was having a shower but I chickened out again.

I'm so terrified that if I make a move he'll tell mum or shut everything down, but I don't know another part of me says if there's a 1% chance that we could be together I should take it?

I dont know, help me please?!