Will a woman be punished for marrying a married man without the knowledge of his first wife, if that causes the ruin of his home and the tarnishing of her reputation by the first wife?

You bear no sin in marrying this man and staying with him, and you are not oppressing his first wife as long as you do not transgress against her or assist your husband in oppressing her. You are not responsible for the deterioration of their relationship. It is permissible for you to waive some of your rights regarding division [of time] or maintenance if you fear divorce.