SPRING VALLEY, N.Y. >> Jean Pierre didn’t kill his kids. It was their mother, not their father, who took the three little children with her in a suicide plunge into the Hudson River this month.

But Pierre, 26, has come under constant criticism. He’s been vilified for cheating on Lashanda Armstrong, labeled a deadbeat on child support and charged with being a danger to children, all of which his lawyers dispute. Armstrong’s family decried Pierre’s decision to hold a separate funeral and burial for the children, rather than the joint service they’d planned. One relative accused him of rigging the guest list at the funeral and even took exception to the way he mourned his children during the service.

Experts say that because Armstrong, 25, of Newburgh died with the children April 12, a human impulse to blame someone has focused on the father.

“It’s really good to have someone to blame,” said Dr. Philip R. Muskin, professor of clinical psychiatry at Columbia University. “Appropriately or not, having someone to blame gives us an answer, and we like answers.”

Pierre’s lawyer points out that he had nothing to do with his children’s deaths.

“He’s in shock that his children died,“ said the lawyer, Stephen J. Powers. ”He’s not looking to accuse anybody of anything but everybody wants to put the blame on him.”

A tendency to blame the victim is not unheard of, said psychologist David Palmiter, public education coordinator for the American Psychological Association

“In this case, one of the victims is the living spouse,” Palmiter said. “His children were killed.”

However, the experts do not find Pierre blameless. If his relationship with Armstrong had been healthy, they said, she probably would have had one less stress factor. In addition, said Gerald Mallon, a professor at Hunter College’s School of Social Work, “a good partner might have picked out the signs of mental illness.”

He pointed to the case of Andrea Yates, who drowned her five children in a bathtub in 2001. Her husband was criticized for not seeing her illness, he said. The ex-husband of Susan Smith, who drowned two young sons in 1994 by sending her car into a pond, was criticized by a pastor for not taking enough of a role in the boys’ lives.

In the Armstrong case, “Obviously, mentally illness was involved,” Mallon said. “That person just clearly is not thinking rationally if ‘Let me just kill everybody’ sounds like a good decision to her. But those decisions don’t come out of nowhere. … You could certainly make the case for the fact that the father didn’t drive the car into the Hudson but the father was probably deeply involved in the reason she drove the car into the Hudson.”

Police said Armstrong was involved in a domestic incident at her apartment just before she drove down a Newburgh boat ramp and into the Hudson with her four children. Killed were Landen Pierre, 5; Lance Pierre, 2; and Lainaina Pierre, who would have turned 1 last week

The only survivor was 10-year-old La’Shaun Armstrong, who was not Pierre’s son. He escaped, swam out and was taken to safety by a woman who said he told her his mother had had a “big, big argument about my stepdad’s cheating on her.”

Another lawyer for Pierre, Michael O’Connor, wouldn’t call it cheating.

“They were not married,” he said. “They had a long-term relationship that was on and off. That’s the lifestyle they chose.”

If Armstrong was unhappy about the lifestyle, that could have been a contributing factor, Palmiter said.

“In general, if a person is in a relationship that is painful to them, that is a top stress in a person’s life. Being in a marriage that’s painful tends to be one of the big ones.”

Muskin warned that the tragedy shouldn’t be blamed entirely on a straying boyfriend.

“Maybe he missed the signs; maybe they didn’t have a great relationship,” he said. “But did he predict that she would kill herself and the children?”

It’s unclear whether Pierre was talking about affairs when he said in a statement he issued last week that “If I could, I would have changed some things in my past.”

“I have been inaccurately portrayed as being directly responsible for the tragedy,” he said.

Pierre, who’s working at a Dunkin’ Donuts in Newburgh, was labeled a “deadbeat dad” in some news accounts but O’Connor said there was never any such allegation relating to his children with Armstrong. Pierre’s lawyers also said that a child endangerment charge against Pierre, stemming from when a 2-year-old boy was found wandering the streets in February, was resolved without a conviction.

He was ordered to attend parenting classes as a condition of a dismissal, O’Connor said, and his lawyers are trying to get that revised because “it would be too sad” now that his children are dead.

The lawyer said Pierre “was very active in his children’s lives” right until their last days.

His decision to have a separate funeral and burial for the children was announced the day before a planned joint service arranged by Armstrong’s family. Pierre said he wanted to grieve for his children privately, rather than at the open service that was planned.

Armstrong’s family was critical.

“She gave birth to them,” said Armstrong’s cousin Channise White. “At the end of the day, no matter what, they are her children. They should be buried with her.”

Muskin called it a decision “that allowed people to target him.”

Palmiter said, “It’s so easy just to say and do things that inflame the situation. If it weren’t for the tremendous pain maybe it wouldn’t be as inflaming.”

The experts said whatever his faults, it’s wrong to blame the tragedy entirely on the father.

“He didn’t drive the vehicle into the river,” Mallon said. “But he has to live with what happened to his children. He will probably carry that horror with him for the rest of his life.”