(m/f) this random morning with my mother in law

To make a long story short. I've(26m) always been flirtatious with my mother in law(Mil) (50f) but it was always in a joking way and she loved to play along. She is about 5"5 with black hair and an hourglass figure. Ive always fantasized about having sex with her but never acted on it

My wife and I married 3 months ago and we're still living at her parents house in the basement until our home is finished being built. My wife had to go out of town for 3 days on business. Which put me in an awkward situation by myself.at the house with her parents. And this morning it got extremely awkward.