Daughter having shower time with stepdaddy

My step-daughter is 18 now and I ended up letting her jerk me off and it was so fucking hot. Then a couple days later, she came and got in the shower with me like a sweet little sudsy angel. I know! I need to stop. But her young tight body, pretty face and youthful giggle make me want to take it to the next level. I don't know how strong I can be.