TIFU during my girlfriend's birthday

I never planned to break up with my gf on her birthday. But it happened anyway. Let me paint the picture. Last night, rooftop, friends, alcohol, DJ, etc. I had too much to drink before having an unexpectedly deep conversation with a dude who was clearly stoned. I didn't know him, but he got my attention when he randomly asked me if I've ever had the misfortune of seeing someone chewing gum with their front teeth. I said if I did, I never noticed. The stoner dude said he used to date a girl who always chewed gum, and she only chewed with her front teeth, which eventually made him tap out of the relationship.

The two of us ended up going down a rabbit hole and unpacking our relationship experiences. I had too much alcohol in my system to go that deep because nothing stopped me from telling the stoner dude that I was planning to end my relationship with my gf after her birthday. Later that night, my gf approached me to inform me that someone just made her aware that our relationship was apparently ending soon. When my gf asked me to confirm if that was true or not, I was at a loss for words, which was more than enough confirmation for my gf to file my silence under "it must be true."

Before I could think of the best response, my gf was gone. She vanished into the crowd, but she didn't stay invisible for long. When I saw her again, she was standing next to the DJ with a mic in her hand and announcing that she was officially single. She made a joke or whatever about wanting a man, not a boy, who at least enjoyed eating ass, unlike someone she dated recently. The DJ, who was not a man or a boy, but a girl, raised her hand like she was volunteering to be an eater of ass. Cut to my gf making out with the DJ while half the crowd cheered them on and the other half were watching me with anticipation.

Needless to say, I left. Hands down the most uncomfortable birthday I've ever experienced.

TL:DR Had too much to drink. Told a random guy that I was planning to break up with my gf after her birthday. Gf found out during her birthday party and made our break up as public as possible by announcing that she was single and then making out with the DJ.