Former Disney TV Prez -- I Did NOT Molest That Boy

David Neuman, the former President of Disney TV, is lashing out at the man who accused him of sexual molestation ... calling the allegation "disgusting."

Michael Egan -- now 31 -- claims Neuman, "X-Men" director Bryan Singer and others repeatedly raped him at pool parties in L.A. and during vacations in Hawaii when he was 15, and Egan claims it went on for 2 years.

Neuman has responded to Egan's lawsuit -- filed Monday -- by saying, "The disgusting allegations made against me are COMPLETELY FALSE."

Neuman goes on to say it's "sickening, and very evil, for anyone to lie like that, let alone in a legal document."