I understand that you're looking for a 3-letter phrase in Dutch that means "terribly painful." However, there isn't a single 3-letter word that perfectly captures this meaning. Here are a few options that come close:
Pijnlijk (6 letters): This is the most direct translation of "painful" in Dutch. However, it's longer than 3 letters.
Erg Pijn (6 letters): This phrase combines "erg" (very) with "pijn" (pain) to emphasize the severity of the pain.
Zeer Pijn (6 letters): This phrase is similar to "Erg Pijn," using "zeer" (very) instead of "erg" to convey intense pain.
Vreselijk Pijn (12 letters): This phrase combines "vreselijk" (terrible) with "pijn" (pain) to highlight the extreme nature of the pain.
Onuitstaanbaar Pijn (15 letters): This phrase uses "onuitstaanbaar" (unbearable) to describe the pain as being so severe that it's difficult or impossible to tolerate.
While none of these options are exactly 3 letters, they all convey the idea of intense and terrible pain in Dutch. The specific phrase you choose will depend on the context and the level of emphasis you want to place on the severity of the pain.