it wasn't a real threesome

My girlfriend is really into the fantasy of a threesome... with another woman or another guy. I wanted to please her and play with her fantasy so I decided to prepare a "surprise" night for her.
We returned home from a night out and we were kind of dizzy from drinking. I started kissing her on the neck and all over her body whispering that I had a surprise for her...She got really horny and she kept asking me what it was. I then tied her hands behind her back and blindfolded her. We got up and went to the bedroom.
I fully undressed her and told her to stand in all fours. She obeyed me. I had already plugged a realistic dildo on the wall and I went behind her. I started slowly penetrating her and I whispered in her ear: "here's your surprise"...I lead her head towards the dildo...she felt it on her lips...she was shocked and asked me: "who's this? I cannot believe that you want me to do that". I pushed her head again on the didlo again telling her to shut up and suck "him".

She was so hesitant at that moment but finally she did what she was told to. She started sucking the dildo with no regrets, believing that it was another man's cock. I was fucking her the whole time and I got really hard watching her enjoying that so much... I started cumming allover her ass and she came moments after me with the dildo in her mouth...I then untied her, she removed the blindfold and she saw everything...she grabbed the dildo, put it in her pussy and told me to fuck her ass...she wanted to feel everything that night even if it wasn't a real threesome.