Gilbert Arenas -- Blasts Baby Mama ... You Blow My Cash On Clothes fo

Ex-NBA superstar Gilbert Arenas UNLEASHED on his baby mama Laura Govan -- claiming she blows the $20k he gives her every month on clothes for Instagram "for u f*cks to hit the like button."

Arenas is LIVID -- and clearly blames Laura for negative stories about him in the media ... in which he feels he's painted as a deadbeat dad to their 4 young children.

Enter Gilbert on social media last night ... putting Laura right in the crosshairs.

"I always read about what kind of dad I am but I've never posted about it so who's telling yall? let me guess the mother RIGHT im a Deadbeat??"

In his rant, Gilbert says he's set up each of his kids with a $300k college fund, plus he pays for everything from private school to food, clothes, house, cars, etc.

Then he goes after Laura -- "She gets 20k a month but if u read what I do then ask urself what does she do with 20k ...she has to feed the kids at home, pay for gas to get them to school and pay her phone bill andddddddd that's it."

He added, "She gets 20k to buy her self clothes for #IG for u f*cks to hit the like button."

"She has 2 million dollar closet but my kids look like their bums half the damn time they get posted and I'm the #Deadbeat....if I'm a #deadbeat and a bad father WHAT the f*ck are the rest of the fathers called??? Yall can call me what u want but i bet yall want me as ur baby daddy smdh."

The fight between these two is clearly nasty -- with Laura having previously asked a judge for a restraining order against Gilbert, though her request was shot down.