Despite him getting a ruined orgasm, I still think you won the bet. Bragging rights, for sure! Plus, knowing you have that power over him, and now having swallowed his cum in front of you like that, will just make him that much more submissive to you I think.
You're a wonderful domme and a great storyteller. Thank you for sharing your adventures with us.
Using the Sync app (on Android anyway), you can hit the settings button while browsing posts, and under settings there's an option right there to hide read posts.
On the web, if you click on your username in the top right and go to settings, there is an option "show read posts". By default I think this is turned on - uncheck the box to turn it off. For a while, this wasn't working, but it seems to have been fixed along the way.