Is it bad that I'm strongly attracted to my girlfriend's 18 year old daughter?

I started dating this woman last year. She's ok. A little chubby but not fat, bubbly personality, works in accounting Asian chick from Hong Kong originally.

But she has this smoking hot daughter who obviously knows it and she plays me like a fiddle. When I go over, she'll come and joke that "new daddy" is here and gives me a big hug and kiss and whispers in my ear that we're going to make a "step movie tonight right?" (her exact words) then laughs and skips back to her room wearing asshole hugging tights or a literal school girl skirt sometimes. She is joking but it is driving me crazy like I'm actually seriously turned on with sweat coming just under my arms and stuff. Her mother tells her what the fuck and apologises to me on her behalf.

This is torture. What can I do?

Is it bad that Im strongly attracted to my girlfriends 18 year old daughter?
Is it bad that I'm strongly attracted to my girlfriend's 18 year old daughter?
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