My slutty mother in law roxana
Similar thing happened with me, except it became a daily thing as she lived with us. Her husband had died 10 years before and had not had sex since then. My wife worked nights and still does.
After a month she started wearing only a robe at night and we watch each other masterbate. A month after that we just started kissing and nightly oral sex and regular sex.
We have slept together every night for 15 years. We love each other and the sex is fucking amazing.
She insisted I fuck my wife every day so she doesn't get suspicious. She knows I only love her and likes that she took me from her daughter.