Sister In Law Gotten Bold And Open With Me

I never thought I would do my sister-in-law while she lived with us. She's a big gal with broad big cupped tits and fat ass. My wife was unaware that her sister was forward and open sexually with me. She wore sheer see thru nighties at times and I caught caught her with a dildo in her hand when my wife out of the house. She knew her sister didn't blow cock. My sister-in-law started teasing me with that that sex toy. She rubbed her breasts with it and licked it at times making sure I was looking.
I was showering and heard the bathroom door open and close. The shower curtain was pulled open and my sister-in-law stepped in nude behind me reaching and fondling my dick making it harden. She kept playing with my cock. " My sister is so lucky ! " as she guided and held it close to her mouth. I grabbed her head and held it there on my crouch. She took it down her throat and I began fucking her mouth. " So big hun ! Ease off please! " as she squeezed tits and played with her big dark areolas.
I stepped back starring on her oversize fat body. " Damn your so fat ! " as I lifted and dropped her folds. " You can do me sexually whenever you feel like, and it be a turn on having the three of us together in the same room having sis watch me take that cock in my mouth while sis toys me.