Recently told my wife Id like to watch her with another man. How do I take the next step?

Recently share with my wife of a decade that the thought of her fucking another man is a real turn on for me. She was more surprised than anything else but never said one way or another how she felt. She agreed to post on another voyeur site and found she was turned on by all the men getting off to her but the intensity of the attention scared her and she said she'd prefer not to post. I'm the meantime she's hinted certain things...like telling me the star football player of her college who had a crush on her on college still reaches out from time to time. I want to push the boundaries but I also don't want to scare her off. Any perspectives of experienced couples but especially the ladies would be wonderful.