The Archdiocese of New York Family Life Office (archny.org/ministries-and-offices/family-life/bereavement) offers resources including bereavement support groups and Emmaus spiritual retreats for grieving parents who have lost a child of any age, by any cause, no matter how long ago.
Calvary Hospital (calvaryhospital.org/patients-families/bereavement-support/bereavement-department-welcome) offers bereavement groups that meet on a regular basis in Manhattan, Bronx and Brooklyn for siblings, parents and spouses of the deceased. A connection to Calvary is not required.
The Respect Life Office of the Archdiocese of New York (lifeofficenyc.org) offers information on many life issues, including suicide and depression (lifeofficenyc.org/suicide-depression).