Wanting To Do Her To Get Relief

My wife's sister was living with us. I loved my wife but she couldn't please me sexually. She couldn't understand I'm an oral sex loving guy. I wanted oral sex badly. I began to get interested in her heavyset sister. At times I saw her fat body when she came out of the shower or changing clothes. She has small breasts compared to her big breasted sister's. I began to visualize her nude and giving me head when her sister went out of the house. When I was having sex with my wife I started to fantasize that I was doing my sister-in-law running my hand over the breasts and squeezing them. I tell my wife to jerk me till I cum , pretending her sister just gave me a fantastic head job and I shot onto her.
I began touching her a bit naughty. I knew it was wrong but I had to find out if me being naughty intrigued her somewhat. I guess it did because at the dinner table when her sister wasn't looking , she placed her hand on my crotch and smiled at me. My sister-in-law was doing the dirty dishes I pressed against her feeling her nipples as she rinsed the dishes. She positioned my hand inside her open blouse causing my cock to harden. " Let'ts go upstairs into my room. " There she pulled out my dick and started giving me head. I loved her mouth sucking my cock with her top off as I played with her nipples and pulled on them. " Fuck me ! " she blurted out as she removed her bottoms showing me her c**t. Instead I placed my head between her fat legs eating her out and tasting her fantastic juices as she forced my head in her and yelled out, " Don't stop ! " My face was getting wet. She positioned and lowered herself on my cock bouncing up and down on it fingering herself. " I wanted you for a long time. I hope I'm pleasing my brother-in-law well enough to screw on a regular bases. That cock is fantastic.