I catch my stepdaughter masturbating and I help her to calm down, but we have sex and I have unprotected sex with her. I would like to avoid pregnancy

I am having regular sex with my 18yr stepdaughter & one day came across hermasturbating I had to console her when she was through. It got very rough when we proceeded to make hot, raw love. She was young, sexually charged and very fit and the erotic tension was boiling and kinky that for an intimate session we came up with.