Brother And Sister

Before July of last year I'd not had sex with someone else for nearly four years.
My wife passed away and at first I just wasn't interested. Time went by and women weren't attracted to me because even though I have a large penis, I'm no oil painting.
Last July I met a guy in his early thirties in my local park, and really not meaning to at all, I began receiving blow jobs off of him.
I'd never had gay sex before, but we got on so good and his blow jobs were absolutely amazing.
Then one afternoon instead of receiving head off of him in my car, I drove us back to my place.
It was the first time I'd fucked anyone in four years and i loved making him cum by thrusting up his cute arsehole.
By October he was almost living permanently with me and I was fucking him at least once a day.
My libido had fully returned and then some and that's when I met his sister.
She's seven years older than her gay brother and for some reason we really hit it off.
She and I had so much fun together over the next few weeks, and even though she knew I was fucking her younger brother, we began having sex.
And it was during a wonderful afternoon of sex with her, her brother walked in on us.
I was fucking his sister from behind when he walked into my home. I wasn't expecting him so I didn't notice him at first, and he later told me he'd watched me fucking her for a few minutes before he uttered "Ugh huh".
There was no nastiness between any of us and after covering up and putting some clothes on, they were laughing together about her enjoying the same cock.
I felt a little uneasy until she left half an hour later. Then not giving me chance to say no, her younger brother sucked my dick still coated in his sisters juices and then had me fuck him exactly how and where id been fucking his sister when he'd walked in.

It's now May the following year and I'm now living with and engaged to my beautiful fiancée.
Her brother and I still fuck occasionally and my fiancée knows that. In fact just recently he stayed over after we'd all been out for a meal.
It got very amorous between myself and her little brother and we ended up having sex on the couch. It just happened, so as he sucked on my cock then rode my entire length, almost to prove he could take it all, his sister watched and masturbated on the chair a few feet away.
It was so horny a situation I didn't last long and came deep inside of him, and that's when with my fiancée saying "Oh fuck yeh" she orgasmed playing with her clitty.

We've not all had sex together and I don't even think (Who knows) they'd entertain it, but id love to fuck them both together.