A gut-wrenching family photo shows the Westchester County teacher who was gunned down by her retired NYPD detective husband in a murder-suicide this week smiling with her kids — as friends remember the mom of three as “truly remarkable.”

A beaming Arlene Connolly O’Neill, 47, is seen posing with the couple’s three sons at a baseball game in a family snap on her Facebook page.

O’Neill — who worked as a fifth-grade teacher at Anne Hutchinson School in the Eastchester Union Free School District — was shot multiple times by her husband, Sean O’Neill, at their Chittenden Avenue home in Yonkers on Wednesday morning.

Sean O’Neill, 54, then shot himself once in the head, the local police said.

The couple’s sons — ages 15, 13 and 11 — were home at the time of the shooting, but were not physically harmed, the police added.

The kids are now being cared for by an uncle, who is a local fire chief, sources told The Post.

The couple allegedly had marital issues for sometime before the deadly blow up, they added.

The school district dispatched a “crisis team” to the school where Arlene O’Neill had taught to meet with grieving students, staff and faculty members, according to a letter sent to parents late Wednesday Other districts in the county had aided by sending counselors to help, the letter said.

A letter from the district board of education to the community on Thursday said members were devastated by “the unimaginable tragedy.”

Mrs. O’Neill was not just an exceptional teacher but also a cherished member of our community who touched the lives of countless students and colleagues,” the letter stated. “We will all miss Arlene very much and will spend many difficult moments grieving her loss.”

A private mass was scheduled to be held Thursday night at Annunciation Church in Yonkers.

A GoFundMe in Arlene O’Neill’s memory remembered the veteran teacher as “a truly remarkable individual: a dedicated, hard-working teacher for over 25 years in the Eastchester School District, a fearless mother, a thoughtful sister and a kind friend.”

“Arlene has spent countless hours shaping the minds of her students, all while raising her three incredible boys … who were her greatest pride and joy,” the tribute read.

“Arlene exemplified strength, kindness, and resilience. She poured her heart into both her classroom and her home, always putting others before herself.”

Any proceeds from the GoFundMe will go to the O’Neill boys’ education and “their talents in both music and sports that Arlene worked so hard to encourage and support,” the page said.

As of Thursday morning, the fundraiser had raked in over $220,000 by Thursday evening.

If you are struggling with suicidal thoughts or are experiencing a mental health crisis and live in New York City, you can call 1-888-NYC-WELL for free and confidential crisis counseling. If you live outside the five boroughs, you can dial the 24/7 National Suicide Prevention hotline at 988 or go to SuicidePreventionLifeline.org.