Losing a Cum Competition Six Times in a Row

My husband has had a partner at his firm for years now that has been just awful. We have been wanting to cut him out of the firm forever, but we can't afford his severance package. He is lazy, brings in hardly any business, and CONSTANTLY tries to fuck me. Literally, every day is him hitting on me, talking about his dick, blah blah blah. Today though, he really stepped it up. He casually said that he would bet (essentially his career) on that he could make me cum before he does. I pretended to be interested and then he really went to town, putting stipulations on what happens if I lose UP TO SIX TIMES. This guy really things he can make me cum once? Let alone six times. So I go home and tell my husband. After some back and forth he agrees that it would be the best way to finally get rid of him. Well, things didn't go to plan. He came in completely confident, and all it took was riding his cock for a few minutes for me to cum. Then he just kept going, and going.