Need help to decide have sex with friend or not

I have a female friend from school, and we’ve been friends for over three years. We often talk to each other over chats. I don't have a girlfriend, and I’ve never been in a relationship before. About two years ago, this girl confessed that she wanted to be in a relationship with me. I politely told her that I wasn’t interested in a romantic relationship, and we continued our friendship and kept talking.

Recently, during a conversation, the topic of sex came up, and she expressed that she would be willing to have sex with me as friends. However, I don’t find her physically attractive — I'm not fond of her looks, the shape of her face, or her skin tone. But at the same time, I have this urge to be intimate with someone. Now I’m conflicted — should I have sex with her, or should I just tell her "no"?