Sister's panties

I've always known I had a feminine side but I'm attracted to girls.I started to notice my sister's panties when I was around 13. By the time I was 16 I had progressed to sniffing tasting and wearing them. Inevitably I was caught one day by my sister and her friend. I was on my bed with just a pair of pink panties on watching panty porn and didn't hear anyone come in. Then I heard Kate my sister shout wtf do you think you're doing. Sally her friend burst out laughing and Kate said are those my fucking panties. I was horrified and tried to cover myself with my hands. They were both in my room now and again Kate shouted well are they. I tried to say sorry but then Sally jumped in saying look Kate look how small is little cock looks in your panties. Kate's anger turned to laughter pointing and saying fuck Michael is that all you've got down there. I was mortified but my cock stayed hard. Move your hands let's see how you look said Kate. I moved my hands slowly and Sally shrieked fuck Kate look he's been leaking precum into your panties. Kate looked saying you dirty little pervert look what you've done to my panties. Then to my horror Sally reached over and ran her fingers along my cock making it twitch. She laughed hysterically and gave it a squeeze. Fuck no I thought as I felt my balls tighten and before I knew it I was cumming into Kate's panties in front of both of them. Sally was loving this shouting look he's cumming inside them. Kate on the other hand was furious. How dare you leave that filthy mess in my panties and to my total shock she ripped the panties off me,cum dripping out and shoved them towards my mouth shouting open bitch. Sally was loving it saying go on Kate make him eat his own cum and she shoved them roughly into my mouth making sure I got every last drop out. That's the start of my now different relationship with my sister.