Piolin -- Sex Accuser Has Been Loco for Years

Legendary Spanish radio host Eddie "Piolin" Sotelo isn't pulling any punches after a former employee accused him of sexual harassment -- telling us the man behind the allegations hasn't been right in the head for a long time.

As we reported, Alberto "Beto" Cortez -- a former writer, producer and performer on the Piolin por la Manana show -- accused Piolin of physically, sexually and emotionally harassing him for 3 years ... but Piolin gave TMZ a statement, insisting it's BS ... and Beto's emotionally erratic history backs him up.

Piolin says he stood by Beto for more than a decade "through all of Beto's personal travails," but Beto went off his rocker in 2012 ... and Piolin could no longer protect him. Piolin says Univision decided not to renew Beto's contract as a result ... and now, Beto's out for revenge.

TMZ has obtained an email sent from Beto to Univision higher-ups -- sent in 2012 -- in which he admits that his life has gone off the rails and he's trying to get better. He was let go shortly afterward. Piolin claims the email proves Beto was nuts before these allegations surfaced.

Piolin is currently off the air as a result of Beto's allegations, but tells us, "I plan to be back on the radio very soon."