My gf found out I cheated on her which led to her opening up to me about liking the idea of sharing me

So I(24M) have been in a relationship with my gf(19F) for a couple months now.
Our sex life always was okey but not fully satisfying. I definetly like it more rough and my gf is more of a vanilla kind of girl or so I tought. Only having sex like once a week even though I could have multiple times a day.

I wasn't even planning on cheating but I went out clubbing with two friends. Went outside to smoke alone since my friends don't smoke and I started chatting to this pretty blond girl. We hit it off right from the start.
After we went inside again and danced together I grinded on her and she pushed her ass into my crotch and was able to feel how my cock grew. Shortly after we went outside and I let her blow me and let me tell you she was so sloppy and so eager to please me which my gf never did. We exchanged numbers after that and keep on texting and teasing each other over the next days until we met up again and this time fucked for real. And we had the kind of sex I was always dreaming of. Meaning full on degration, face slapping, spanking, spitting in her face and even anal!

Well eventually my gf apparently opened up my phone and to be honest I don't even remember the reason anymore because after she saw those texts followed a big and long back and forth of arguing. I actually expected her to dump me on the spot but she didn't. At one point we just split off and I layed down on my couch and she went to the bedroom.
To my surprise later she came to me while I was already half asleep and she told me she over exaggerated which definetly took me by surprise. We both apologized to each other and one thing led to another and we were undressing and having sex!
It all felt completely different. She was way more energetic and tried to please me way more than I am used from her.
During sex she was actually asking me all kinds of questions about that other girl. This was a site of her that I didn't even know existed.
She would ask me if her pussy was tighter or gotten more wet than hers. Or if I enjoy the sex with her more. If I liked the tought of cheating on her.
This night actually was the best sex I ever had with my girlfriend!

Over the past couple of days we did talk a lot about all of this and she admitted to me that she has some kind of cuckold fetish even though she never used the word cuckold. She rather said that she likes the idea of sharing me and she even said she might be open to watch me have sex with someone else in the future!

So yeah a really surprising turn for me but I am really looking forward to exploring this kinky side of my gf in the future!