Sis Got A Car From Dad

My sister is admittingly pretty slutty. Brings home a guy every 2 weeks or so and it's usually pretty late. It's just my dad, sister and myself that live at my place since our mom passed away 2 years ago.

My sister had turned 18 a few months ago and not to my surprise I got home pretty late and I could hear her moaning from her bedroom. I went looking for my dad in his room to give him back his key cause I was using his car. I didn't find him in his room so I called out to him and just at that moment I heard the noise from my sisters room stop. So I went up stairs and as I'm heading up I hear a door open downstairs and didn't find him anywhere up stairs. I come back downstairs I see him on the couch which is right by the front door. I asked where he was and he said he was in the bathroom. In my mind I know that's bullshit cause the downstairs bathroom door was open when I first walked by it. I gave him back his keys and headed to my room and it's on the way to my sisters room which just so happens to be open now. I look in see her fixing her hair. No words were exchanged but she knew I knew what she was up to.

A few days later, magically a car showed up in the driveway with her name on it. I don't even know what do even do about this but to just accept it.