He starts undressing you

You hear and feel the fabric of your black dress tear as your captor rips it off. Suddely you feel a sharp object at your throat.

"I have a knife here," he lets you know, letting it trail down the front of your body, ending at the top of your rough pubic hair.

You let out a moan of pleasure and fear. This is exciting you.

Roughly he squeezes your breasts and lays a few kisses on you neck and chest. He pushes his mouth against yours and forces you to open it, letting his tongue freely explore your mouth. The knife rests against your right breast. The man parts your legs and kneels between them. He is still fully covered as far as you can tell. He lowers his body towards yours and pushes his groin into you.

His moan is enough to make you push back a little which seems to excite him more.

Before you can realize what's happening his hand comes up and slaps you while he pushes harder into you.