NHL's Alex Galchenyuk

NHL player Alex Galchenyuk -- who allegedly hurled racial slurs and made threats toward cops during a hit and run arrest last week -- is apologizing for his "deeply disrespectful and despicable behavior" ... saying he's going to seek treatment through the league's player assistance program.

The 29-year-old center was arrested on July 9 in Scottsdale, AZ after appearing to crash his car into a sign. During the traffic stop, cops say Galchenyuk was aggressive and claimed to have connections in Russia who could go after them.

"I'm gonna chop you, your wife, your daughter," Galchenyuk said, according to the police report. "One phone call and you're all dead, your whole family, your bloodline is…