Am i bi? we were all 25 and in college at the time...regrets

So i (female) was coming home from a really bad day at school. My mom and dad were out for the week so me n my sis were home alone. I walk to the door n i hear moans and grunts of pleasure...sex moans. And one was obviously my sister. I ran in and i saw my sister and her super hot (no homo) best friend (also female) om the couch and my sister was sucking her friends vagina...hard. And her friend saw me and grinned. My sis turned around also. I just stood there in shock. Her friend said in a slurred voice (obviously drunk) to my sister to go on. My sis did as told. A few secs later her friend told me i should join. I thought about it and started to back away slowly. Her naked hot n wet friend came up to me and pulled my skirt and panties down and started licking my clit. I groaned and fell on the chair. My sis came over and (she was drunk) ripped my shirt off and sucked my tits. This wen on for about 10 minutes and then i started sucking my sis and her friend... Her friend then said to stop and she sat up and my sis started to try to get to her tits but her friend slapped her and left the room and came out with a GIANT dildo. She took it and shoved it in my sisters ass. I sucked their pussies and they did this to me and i did this to her friend. Then we ended about 5hrs later along with many other sexual activities.It was only 8 but we were exhausted. Her friend got dressed and crashed on the couch. My sis n i continued f**king and then we fell asleep. We havent spoken about it since... And idk if she remembers cuz she n her friend were trashed.
Am i bi? IIN?