Tua Tagovailoa -- who won a national championship alongside Henry Ruggs at Alabama -- choked back tears as he addressed his ex-teammate's fatal DUI arrest after practice Wednesday ... saying, "You’d never think that this guy could hurt a soul."

The Miami Dolphins quarterback appeared emotional and upset over the tragedy ... sharing his condolences to those close to the 23-year-old woman who died as a result of the crash.

"That’s tough," Tua told reporters. "My heart goes out to the families affected by what happened, the choices and decisions."