My daughter wants me to spank her?? Please help!

Ok to begin my daughter is 19 years old and asked me today to spank her as punishment. This really surprised me. My daughters and I are very close and don’t have any tension between us. She recently cheated on her boyfriend and didn’t tell him. She came to me about it and has been stressing about for a week now. I never spanked my kids while they were growing up and my parents never did it to me either. I guess I am neutral on the whole subject matter. I don’t want my daughter to kill herself from the guilt and stress, but she also did cheat on her boyfriend. What would you do because I am really at a crossroads here.