Judge Rips Allen Iverson -- WORST PARENT EVER ... Says Judge

Allen Iverson -- once considered the best player in the NBA -- is a terrible parent ... a horrible, irresponsible, pathetic excuse for a parent ... this according to an Atlanta family court judge.

Iverson just officially became a single man -- after the ATL judge signed off on his divorce from Tawanna Iverson ... the mother of his five children.

But in the final divorce decree, the judge UNLOADS on A.I. ... saying:

"[Iverson] does not know how to manage the children; has little interest in learning to manage the children and has actually, at times, been a hindrance to their spiritual and emotional growth and development.

For example, he has refused to attend to an obvious and serious alcohol problem, which has caused him to do inappropriate things in the presence of the children while impaired.

He has left the children alone without supervision. He has left his young daughters in a hotel room with men who are unknown to the mother."

The judge has awarded Tawanna legal and physical custody of the kids. Allen has some visitation rights ... but ONLY if he abides by certain conditions.

Among them ... Allen must NOT drink a drop of alcohol for the next 18 months. And there's more ... until all of his kids become adults [18+], he can't consume alcohol within 24 hours of the times he has the kids.

He's also been ordered to see a shrink and attend AA meetings for a year.