My Mother's Bisexual?

I can't believe that this happened, but it has turned me on no end. I'm an 18 year old student at my local college. I've been exploring myself online for a while, and found this site. I knew I had to tell you about this. My mother is an attractive older woman. My dad left us when I was young and she's dated but never anything serious. After my "sexual awakening", I would often try to listen in on my mother as she had sex with some of the guys she'd bring home after a date. She'd send her best friend Patty, who was watching me, home and take the man to her room. If I listened closely I could hear the grunting and moaning and squeaking of the bed. It would always make me wet and I'd play with myself the whole time. Not long ago, my school had a flood that caused them to send the students home. They called the buses and took us home early. I thought I'd have the house to myself and was actually getting horny, thinking of rubbing myself to a fantastic orgasm. To my surprise, my mother's car was in our driveway. I thought that odd, but then figured that maybe she was home to get something. She didn't work far from home. As I opened the door, I was about to call for my mom but stopped. On the floor in the entryway were a pair of panties. I was floored. She was home to get a little something. I wondered if it was a guy from her work. As I went from the entryway, I noticed an occasional piece of clothing on the floor as I headed to the hallway to our bedrooms. I could also hear some moaning and giggling. Then something struck me as odd, I thought I heard two sets of female voices. Just then I realized that there were two sets of clothing periodically discarded on the floor. But both sets were women's. Was she having a threesome with a couple???? I had surfed porn enough online to know about threesomes and the idea of sharing a guy with another girl was kind of perverted, but somehow turned me on. I decided to sneak down the hallway and see if I could hear anything more. As I got to her bedroom, I saw the door was cracked open. I had never in a million years thought I'd see my mom doing anything, although I imagined what it would look like as I heard her getting fucked. When I peeked in the crack I was floored. Not only was there no guy, but my mother was buck naked with another woman in the 69 position. Mom was on top and her partner was on the bottom. I could see my mother's face clearly from the side as she ate the pussy of the other lady. But I couldn't see a lot of the other woman. The two of them really started moaning and moving around and I knew they were approaching orgasm. I was so turned on that I couldn't keep my hand out of my pants. I was soaking wet. Then my mother's lover stiffened and her legs pressed hard against my mom's head as she convulsed in orgasm. When the waves of pleasure subsided, she sat up, still sitting on her lover's face as she continued to have her pussy licked. Mom's face was a mask of pure pleasure and it turned me on to see her like this. In my excitement, I couldn't withhold a moan of my own. My Mom heard it and quickly looked towards the door. She seemed unsure whether to say she heard something or just continue getting pleasured. Just then she seemed to focus on me, as hidden as I tried to be I didn't realize that I could be seen in the reflection of the hallway mirror. She climbed off her lover and only then did I see it was her best friend, Patty. I always liked Patty, she was like an Aunt to me. But now I saw her for the hot, horny, sexual person she was and I got even wetter than I ever thought possible. Patty sat up and asked, "Did you cum?" My mom told her, "Not yet." "Then what. . .", Patty started. But Mom just headed right to the door, her full but slightly sagging tits swaying and her full bush in display, wet with Patty's spit and her own juices. I didn't know what to do. My pants were open and around my thighs, my hand buried in my pussy and soaking wet. Mom pushed open the door and Patty saw me standing there. Mom lightly grabbed my arm and slowly brought me into the room. Patty tried to hide her small but perky tits and shaved cunt, but them when she saw where my hand was she dropped all pretense of hiding. My mom soothed my fears as she brought me to the bed and said that my curiosity and interest is perfectly normal for a young woman. She said that her and Patty had been having fun since they were teens and it's also normal to have sexual encounters with female friends, regardless of what the really conservative people say. Patty faced me, sitting with her legs drawn to her chest, but her wet swollen pussy in clear view. Mom told me I was welcome to watch them finish and I could get more comfortable if I wanted. I spared no time in dropping my pants and removing my shirt and bra. My boobs were smaller and perkier than Patty's which were perky but full and round. Mom sat next to Patty, her legs splayed in front of her, her body on display. Her hand slid down between Patty's legs to ease any discomfort she might have been feeling. Patty did likewise and started to circle mom's clit. Since my Mom hadn't gotten off yet, Patty really went to town on her. I sat facing them, cross-legged and buried my hand in my crotch. They both intently looked at me, playing with my own pussy as I watched my Mom and her best friend play with each other. Mom said she was proud that I was able to pleasure myself. That sometimes guys wouldn't do it for me and it was important that I could do it myself. Or have a friend like Patty who could do it for me. Sometimes when Patty would rub her clit hard, mom's legs would spasm. It was such a turn on watching these sexy older ladies pleasure each other. I took a chance and uncrossed my legs, letting them drape over my mom's legs. So we were facing each other, pussies exposed and being rubbed. Mom got wetter and wetter and asked if I was close. She said she wanted to cum with her little girl. That thought, so perverted, yet such a turn on sent me over the edge. My eyes rolled up and my legs clamped together as my vagina spasmed around my intruding fingers. Mom let out a guttural "Yes" and her legs stiffened, sticking out straight in her V sitting position and her juices flooded Patty's hand and her sheets. I realized that I left a nice wet spot in Mom's bed also. She told me that was ok. The three of us headed to the kitchen naked and discussed what just happened so that we'd all feel comfortable with it. Mom also said I can masturbate with them any time, but only her and Patty would touch each other. She also encouraged me to find a trusted female friend that I could masturbate with and maybe fool around with. I love my Mom and her friend Patty and look forward to the next time I get to watch them.