SD watching me jerk off

One summers day, when i was off work, i decided to watch some porn in the living room, i was home alone, so i thought, i lay on the sofa without any trousers or boxers on stroking my hard cock with my wifes panties which was a normal activity for me when i had the house to myself.
At one end of the lining room is my tv, opposite end of the open plan living/dining room has a set of patio doors,
i noticed a shadow reflecting in the tv screen, without just turning round i slowly moved my head just enough the glance my teen sd watching me from outside the doors, this didnt put me off and i adjusted myself so the she would have a perfect view of me stroking my now even more hard cock.
I put on a good show for her slowly moving my hand up and down the shaft and also wrapping the panties around my cock, i jerked off for as long as i could knowing she was watching, it turned me on so much hoping she had her hand inside her panties fingering her tight teen pussy.
I made sure she got a perfect view of me cumming, shooting cum all over myself and smearing it over, then slowly wiping it up with her moms panties.
When i had finished and got up she had gone, I hoped she had gone off to masterbate thinking about me wanking my hard cock or had allready cum.
This was the first event out of a few more naughty things that happened with her.