Jax Taylor's Estranged Wife Brittany Cartwright Says He Desperately Needs Vasectomy

Jax Taylor’s tapping out of fathering any future children -- he wants a vasectomy, and his estranged wife Brittany Cartwright’s all for it ... making it clear the man can’t keep it in his pants anyway.

During "The Valley" reunion Tuesday, the father of one explained he's ready for the snip -- and Brittany didn’t miss a beat, saying he desperately needed one or he'd end up with "20 baby mamas!"

The zingers kept flying in front of their shocked faces with Brittany calling Jax "disgusting" and snapping, "I wouldn’t touch that dirty d*** with a 10-inch pole!"

But Jax clapped back fast -- dropping a bombshell that Brittany tried to hook up one last time just months before the reunion ... allegedly at Hooters and even the aquarium.

Things spiraled fast -- the exes accused each other of hooking up with porn stars, with Jax claiming he found condoms all over their house ... but Brittany fired back: "Hey, at least I use them!"