I think it would be worth an apology for the way you went at the teacher. Explain that they crossed a line in their discussion with your son; what they said was in no way okay. The teacher needs to recognize that there are times when they should simply comfort a student, then get in contact with the student's parent if they are concerned.

You are grieving and grief sometimes causes people to become reactionary. While you were completely right to confront the teacher, perhaps the way it was delivered is what deserves an apology and a calm conversation. I suspect the teacher feels awful for the way they handled your son's sadness and recognizes that they overstepped their boundaries.

If they don't recognize that, well, that's really unfortunate and speaks to their character.

ESH but it's nothing a calm conversation can't clear up.