Sniffing Mother-in-laws Panties

4 years ago I first met my wife to be and at that time she was still living at home. Sometimes I was allowed to stay with her over the weekend.
My girlfriend was 19 at the time, I was 26 and my gf's mother was 41 - blonde, busty and stunning.
One evening I see her mum leave the bathroom after her evening shower so I go in and my eyes are drawn to the laundry hamper, which has my future mum in laws white lacy panties hanging over the edge. I had to check them out. I went straight over to the hamper, picked up the panties and examined the crotch. It was wet. Very wet.
I brought the crotch to my nose to sniff and then licked it. The taste was amazing.
Holding the panties to my face I unzipped with the other hand and pulled out my cock to wank off.
I'd only just started and my cock was rock hard when the bathroom door opened and my future mum in law walked in and saw what I was doing.
I don't know who was more surprised or embarrassed.
I quickly dropped the panties back in the hamper. Her eyes followed the panties to the hamper and then came back to meet my eyes....and then dropped down to my erect cock.
She didn't say anything, just made an "O" shape with her mouth, shook her head and walked out, closing the door behind her.
I didn't follow her and never mentioned the incident to her or to my girlfriend.
Then as I was leaving late Sunday. I went to say goodby to the future mum in law and she smiled at me and said that she can see why her daughter fancies me. Patted my crotch and handed me her used panties.
I quickly put them in my pocket, kissed my girlfriend goodbye and drove back to my flat, where I had a long satisfying wank while wearing the panties over my face.
That's all that happened.....no follow up.