It is indeed tough to know those close to you in pain for whatever reason. I saw my dad cry only twice (his mom and dad's passing) until my brother passed away at 18 years old. It's tough to know what to say to someone in that position (and I usually say something stupid), but the point is just to stick together (even if its over the phone) and be there for each other. Everyone reacts differently to adversity, some people shed tears, some people get angry and others do both. There is no shame in either. We are only human.

Good luck helping your parents through this. I wish them and you the best.