I need help telling my closest friend that I saw his boyfriend on a dating app

So one of my closest friend recently got a boyfriend and now he’s the happiest guy ever I’m a closeted bi guy but he kinda knows it, so I sometimes go around in dating apps looking for men and when I did today I found his boyfriend should I tell him and basically confirm that I’m bi and ruin he’s relationship that he wanted for so long or should I just leave it?