If someone close to you told you they were diagnosed with a potentially deadly disease, would you be able to "be strong" for them or would you be a crying mess?

if you knew someone very close to you, like a close family member, was just diagnosed with a potentially deadly disease, for example cancer, would you be able to hold it together when you saw them? or would you be a crying mess?

i know people say “be strong” and “be supportive” but would you really be able to?