Usher Breaks Down in Court Over Bad Dad Allegations

Usher broke down in tears today in an Atlanta court -- after his ex-wife's attorney insinuated he cares more about partying than he does about his children.

Usher was on the stand for hours today in his ongoing custody trial with his ex Tameka Foster -- and during questioning, Tameka's lawyer whipped out photos of the singer partying in Europe in February.

Usher's fighting for more custody with his kids -- but Tameka's lawyer was trying to prove he'd rather go wild at a nightclub than be a good dad.

Usher was also grilled about his alleged drug use. The singer admitted to smoking pot in the past, but when the subject turned to his alleged ecstasy use Usher's lawyer objected.

Usher insisted he never used drugs in front of the children -- an allegation Tameka made early in their custody fight -- but hedged on the subject of seeing his children while under the influence.

The trial will continue tomorrow.