Is it normal that i wanna have sex with my dad`s girlfriend?

Ok so, my dads girlfriend is so sexy. She leaves her thongs laying aroud the house,and I smell/play with them. I masturbate to her. I even caught her changing, she was half naked, nothin but a thong on and she smiled at me! She smiles and winks at me alot. I stare at her ass as she walks past. Is this normal? How can I get her to have sex with me? Does she want to have sex me?