Watching My Roommate and Her Date

I'd told my roommate Diana that I'd be coming home late, which was true, but I'd forgotten a book I'd promised to lend someone, so I had to drop by the apartment quickly. Walking down the hall, I heard her moaning and calling out to someone named Louise. I stopped short when I saw that her door was open. I wasn't sure I could walk past it without being seen. I waited while the moans subsided and then took a quick peek in her room. Louise was lying spread-eagled on the bed, eyes closed, her head propped against some pillows. She was caressing Diana's back and hair while Diana sucked on Louise's nipple and stroked her inner thigh. I knew I should move away, but I was mesmerized. I caught glimpses of Louise's pussy, her lips swollen with excitement. Diana was bent forward at the knees, giving me a clear view of her recently satisfied pussy, juices still running down her thigh. I looked down and noticed that I was fingering my hardened nipples through my blouse and flimsy bra and realized I was getting really wet. Louise opened her eyes and looked at me in shock, then smiled when she saw me fondling myself. She gave me a little nod, which I took as an invitation to stay. I undid my blouse and pulled my breasts out over my bra, cupping them gently before getting rougher with my nipples, pulling and twisting them hard. Diana had moved down to lick Louise's thighs, leaving Louise free to caress her own breasts, which she did while staring at my movements. When Diana began licking Louise's clit, I couldn't take it anymore. My hand crept under my skirt to push aside my flimsy thong so I could reach my slick, engorged clit. I tucked the front of my short skirt into my belt so Louise could watch if she wanted and then slid my fingers back to my wetness, stroking the sides of my clit slowly and gently. I wondered what would happen if I walked over to Diana and began licking her beautiful clit or fingering her hard from behind. The thought sent me close to the brink, but I pulled back just in time, moving my fingers away from my pussy to rub my juices on my now raw and sore nipples. Louise was still staring at me, and I could tell she was getting close herself. I rubbed my nipples gently a bit, enjoying the stinging, before I moved my fingers back to my clit. Louise was moaning and rocking her hips against Diana's mouth, her obvious pleasure sending me quickly over the edge to a stunning climax. Louise saw me spasm in orgasm and quickly and loudly came herself. The sight of her bucking hips made my pussy twitch some more. I don't know if Diana knows about this incident or not, but I'm trying to get up the courage to approach her to see if she's interested in some fun. She's long turned me on in a major way.