Tmi- a lot

My husband and I were in the middle of making love and he told me his fantasy was for another man to have sex with me and for me to come home and have him eat me out with another mans cum. I got up, got dressed, said ok and left. I'm sitting at the park crying. I text and asked if it would ruin our marriage and he said no. I don't know what to do. I'm torn!!!!