Can I marry somone who has committed Zina (premarital intercourse)?

I am engaged to my cousin. Recently, I came to know that she is having an affair with another cousin of ours. She accepted her mistake, and she was sorry for that, but she still wants to marry me. I am pretty sure that she had intimate relationship with him, but she denied it when I asked her. But her mother admitted it indirectly, and she is very close to her mother. **Question**: Can I still marry my cousin who may have had premarital intercourse with my other cousin?