How having a child with special needs changed Martin Nievera

He wasn't the best husband, but at the very least, Martin Nievera said, he could strive to be a better father.

Having Santino, his 12-year-old son with former partner Katrina Ojeda, has been especially transformative for the balladeer. Because Santino is a child with special needs, Martin has had to redefine what his earlier notions of what being a parent entails.

"He has really changed me a…