ANSWER:

You must not lie as this is a major sin. However it’s not permissible to reveal your sins as well, so you must dodge the question and make them feel that you’re offended by such a question and change the topic. 

What should i do if someone confronts me about a sin i have done? should i lie about it and say i didn’t. What if they ask me to swear by Allah that i didn’t do it? In this case not swearing would obviosly be like telling that person i have commited the sin? So what should i do in these cases?