Rapper Big Sean called off his engagement to Glee star Naya Rivera -- and things have quickly gotten nasty.

After the announcement was made Wednesday, Naya took to Twitter to accuse her former flame of stealing her jewelry. She tweeted, "Big Sean, stealing Rolexes from a lady's house now. Maybe cuz I'm on Glee and making more money or something."

But sources tell TMZ that "the watch was Sean's in the first place -- he bought it for himself when he became successful. Sean gave it to Naya to wear...but it was never hers to keep."

In making the break-up announcement, Sean's rep also insisted that "recent rumors and accusations" had nothing to do with the split. TMZ sources says it was because "Naya was too controlling and too jealous of the women he worked with and met on tour."