Caught wife with father

Caught my 50 year old wife with her 75 year old father.

Short but true story
Came home early from work one day ,let myself in backdoor. I heard moaning coming from up stairs, I sneaked up stairs and what I saw blew my mind my wife was on all four's and her 75 year old father behind her fucking the shit out of her, I just stood there shocked, I couldn't speak, then I realised my cock was solid, I took it out and started stroking, he pumped his big cock into her she was telling him to fuck her harder I started coming all over the landing, then he started grunting like an animal and it was obvious he was coming inside her. I slipped back down stairs. Went for a walk to clear my head came back 30 minutes later they were in kitchen having coffee.
Her dad left after about 20 minutes, I was horny as fuck so i bent her over the armchair and fucked her hard her dad's come still inside her.
A couple of nights later we were in bed having sex ,I wanted her to tell me she was fucking her dad, so
we were talking about sex with strangers.
I told her I would not mind if she had sex with someone else as long as she told me. She still would not say what she done.
Couple of weeks later we were over visiting her parents,
her mum asked me to slip around to shop for some milk when I came back the wife and father were missing, where is jess I asked her mum ,oh her dad is showing her the work he done in the bedroom,
I told her mum I was going to bathroom, sneaked up stairs, and in the bedroom heard the sounds of sex,
slowly open the bedroom door just a bit and there was jess lying on bed legs akimbo and good old dad licking her pussy, slowly closed door and went back down, couple of minutes later they came down acting like nothing happened.
On way home I couldn't hold it in any longer, so I just said
saw your dad licking your pussy, she burst into tears.
So I stopped the car and told her it was ok that I had known for a few weeks.
She came clean apparently he had being fucking her since she was a 19.
Went home and fucked all night she still let's him fuck her occasionally but I get to watch.