My ex’s sexy sister

My ex of six years had gotten busted cheating on me several times, and had finally just said she was a slut and didn’t want to stop fucking other guys. We had a daughter together so I stuck it out, she still gave me plenty of sex as well and had really good pussy for such a fat girl. She loved sucking cock too which will come into play later.
Her sister had just graduated and turned 18 and wanted to stay with us to get out of her parents house and live a little, I happily obliged, just having her slim sexy young self around to look at was nice, and she was really good to look at. She was very friendly towards me as well. By the end of the first week she was sitting in my lap regularly, giggling as she felt me get hard in my pants. When the gf noticed we just played it off. The next week while she was at work I was in the shower and her sexy sister steps in. Finally got to see what she looks like naked and I was impressed, she knelt and took my cock in her mouth and it immediately got hard, she paused and said, I know she cheats on you, and I want you to fuck me! Then she finished sucking me and it didn’t take long til she got her mouthful. She gulped it down and smiled at me, and I cut off the shower picked her up and carried her to the bed her sister and I share, laid her on her back and spread her legs open and tasted her young sweet pussy, and it was so delicious, I sucked her juices from it and nibbles her very prominent clit, she squealed and eventually came on my face.
Up til now her sister was clueless, As we kept having our fun and began to fuck regularly we decided to take it up a notch, I was going to fuck her brains out while her sister lay beside us. One night we worked up the courage and her sister came into our room after hours and I’d made sure my gf was sucking my cock and we were both naked when she came in. Mmmm I want some! She cooed! Come here I told her as her sister spit out my dick and began to protest i put my hand over her mouth. No, you let your little boyfriends fuck your fatass whenever you want and tell me you just can’t help it, DO NOT deny me her! She looked at me, tears welling in her eyes and said but she’s my sister.... I don’t give a fuck, she’s sexy and she wants me, I never stopped you, and I stood and grabbed her little sister and kissed her as I slipped her g string off and began to tickle her pussy lips. Now watch, I barked as I bent the cute girl over in the bed and animalistically rammed my whole dick in her, making her scream out FUCK! Mmmmm baby your pussy is so tight and warm, not like your sisters! Your only the second man I’ve let fuck it that’s why it’s so good she gasped between moans. I fucked her quick and hard with no remorse tossing her all about right beside her sister, and announced loudly when I was about to nut, and she said quick pull it out, and I refused and came deep into her and it felt so good. Her big sister sobbed into her hands as I slipped my dick out of her sis and she said, “do you want me to have a baby for you? I hadn’t thought about it but I did and when I told her she said it made her the happiest woman alive.
She definitely got pregnant too, and her sister moved on once she was able to financially, and I married her sweet little sister. We made sure to give her big sis plenty of shows before she managed to move out, I blew so many loads into her little sis in front of her. Funny how one woman’s cheating caused us to have a wonderful family.