The Brooklyn man suspected of savagely stabbing his girlfriend and her two little girls to death was charged yesterday with three counts of murder and ordered held without bail.

Jermaine Ruiz, 24, stabbed Jessica Ybe, 22, and her two daughters, ages 2 and 5, more than a dozen times each, said police — who revealed that the couple’s infant twin daughters were also in the East Flatbush apartment but were spared.

Police were tipped off by Ruiz’s father, who went to the 45th Precinct station house Thursday afternoon to say that his son had confessed to the grisly crimes.

When Ruiz answered the door at the apartment, cops spotted Ybe’s body partially wrapped in a black trash bag.

The corpses of the two younger victims — who were not fathered by Ruiz — were found wrapped in a rug, cops said.