Choosing What Path To Tread

Apart from the once a month visits to his house for sex, he also takes me away on holiday for a week, twice a year.
He practically brought me up when my mother died, as my father was a drunken mess.

At the age of seventeen I walked into his home and caught him fucking a young guy my age. I got super jealous and needed to know why he hadn't wanted me sexually.
That afternoon we had sex for the first time. I sucked his cock for a long time, then he rimmed my arsehole until I very nearly cum.
When he slid his cock up my rear, I tried to pull away, but he held me saying I'd eventually love his dick being inside me. And he wasn't wrong.
We sucked and fucked all afternoon and I soon learned just how much I loved him sexually, as much as I already did as my uncle.

I now live with my girlfriend in a different town to my uncle. She knows he raised me, but she doesn't know we fuck every time I visit him (?).

The two holidays a year he takes me on we have sex multiple times a day, every day.
It's our time together and each time I fall helplessly back in love with my uncle again.
He's a very busy wealthy man having two businesses, but he takes time out to have fun with me and I absolutely adore him for it.

In a couple of months time, he's selling one of his businesses, and he'll have a lot more time for himself.
He's asked me if I'd like to move in with him and learn about his core business and one day, run it.

I'm now torn because I desperately want to, but also enjoy being with my girlfriend. She, I think, suspects I'm bisexual but hasn't directly said anything. However she has mentioned several times that I'm a feminine type of guy. Someone she said, gay men would love to fuck.
I'm now wondering if I should tell her everything and let fate decide where my life goes.