I think I just outed myself

Let me start by saying I'm a lurker under a different username, and this username I use to post to certain subreddits, since some friends know my reddit username.I'm a 25 year old gay male, and I am pretty closeted. I have groups of friends who know I'm gay, and others who don't. My family doesn't know either. My dad was raised in the 50s and still only refers to gays as fags. I hear him say hateful things about gay people frequently, and it breaks me every time to know someone I love despises who I am. It's worse because I still live at home while I study for the CPA exam, after which I plan on moving out once I get a job in the field. But as of now, I am pretty reliant on him.Anyway, I live in a high ranch. My room is on the bottom floor with a living area and the back door, and my dad and two sisters live upstairs with the rest of the house. Every now and then I do invite guys I know over for a hookup, and they enter and leave through the back door. (No pun intended.) Tonight I hooked up after a long time, and it was completely worth it. Except for the fact that after I kissed him and let him out, I went back to change only to come out of my room and see that my sister was laying on the couch near the back door the entire time. (It was dark) I don't know if she was there when I let him out, or if she got there within the 2 minutes I was changing. How do I approach this situation? We don't get along very well, and sometimes she will call me a faggot when we fight, even though she has a gay friend. I just don't know where she stands on this issue.