My Engagement Night Slip-Up

I’m so conflicted about last night. I’ve been engaged to my partner for a few months now and everything has felt perfect, until we decided on the bed as our wedding present from me. It’s supposed to be our first time together, really committing, you know? But yesterday when she was out running errands, I couldn’t resist. She left her vibrator lying around after one of us got a little too playful while talking on the phone. I just wanted it for a second and then put it away, but next thing I knew, I was sliding the bullet into myself, imagining my fiancée’s hands, exploring my body like she promised when we get married. It felt so real, and yet completely out of place, how could I betray her like that? But damn did it feel good. She’s coming back soon, and the thought of telling her makes me sick with guilt. I can’t lie to her, but now I’m scared she’ll break off our engagement. And worse, what if she finds out herself somehow? We’re both adults here, right? I know we agreed on this night being sacred for us together, but last night has left me in a confusing mess.