how can I confront to my stepmom?

𝔂𝓪𝔃𝓶𝓮𝓮𝓷

how can I confront to my stepmom that I’m into her? I’m not bisexual sorta like bicurious because of the feelings I have for my stepmom, she’s 35 and I’m 15. her and my father have been married for 11 years and she has kids of her own and I’m just her step daughter. I haven’t been around my mom much but I have been around my stepmom a lot (the whole summer and might move with her and my dad for a while). me and her have been talking a night until 4 in the morning but I was to nervous to tell her how I really felt. she cares for me and loves me even though I’m not her daughter. Me and my dad are close but he can get pissed off easily so I don’t wanna tell him how I feel about his wife. can someone please help me?? should I just wait until future preferences or should I just tell her while me and her are alone again?