Britney's now ex-boyfriend David Lucado sucks... After 18 months of what everyone believed to be beautiful, relationship bliss, he did the unthinkable.

He CHEATED on Miss Britney Spears!

What's worse? It's all caught on video and that's the only reason his scummy cheating ways were ever brought to Britney's attention.

Britney dumped him faster than you can say, "Britney, b*tch!" And sent out this very telling tweet:

 Then she posted this adorably dorky video about her shi**y day!

TMZ was told David is still, "very, very in love with Britney." Well, you should have thought of that before you made out with another woman.

The good news? There's still hope she'll get back with Justin Timberlake! (PLEASE PLEASE PLEASE)

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