If Wen Jing wants to sue the man, she needs to report the case to the local police as soon as possible and have a medical examination to determine whether sexual assault has occurred. If a sexual assault does occur, the police will conduct a criminal investigation on the man. In this case, the man's voluntary defense may not be recognized, because Wen Jing can't effectively express his wishes when he is drunk, which is considered as rape.
If the allegations of sexual assault cannot be confirmed, Wenjing can also seek civil compensation. In this case, she needs to hire a lawyer to bring a lawsuit to the court. The lawyer will help her find evidence to support the accusation and represent her in court. A man's active defense may affect Wen Jing's case, so she needs to be prepared to refute and prove his accusation wrong.
No matter which way you choose, Wenjing needs to seek professional help and support, and needs enough courage and determination to get a fair and legal result.