Feel a little guilty

I am 16 and I have had a crush on my step father since before my mom married him. She is a nurse and works 3-11 at a hospital, so I would tease my step dad each evening she was at work, walking around in my underwear, sitting in a shirt and panties with a wet spot on my panties, to finally sitting in just a short nightgown with no panties on, sitting so he could see my pussy, he finally got the hint, now when mom is at work we are fucking. I do feel guilty that my step dad is cheating on my mom with me, but the sex is so good.