FIRST, CONSIDER NOT CRYING
"Breaking down" does not necessarily mean crying. Watch TV News. Watch people in horrifying situations. Not all of them cry. Fighting hard not to cry is a great deal more moving than crying. The best coach I had told me NOT to cry. Leave the crying up to the audience. Fight the tears. It's much more effective.
Let the lower lip quiver. Fight it. Quiver. Fight. Clamp your lips tightly together (as if mimicking someone without teeth. (The opposite of pursing the lips.) Loosen lips. Look down. Raise cheekbones toward eyes. Blink back the tears. Stare. ALTERNATE all these suggested ways of being tearful without crying.
The problem with crying is that the character has to cry but not the actor. And that is TOUGH. In addition, there is nothing quite so damaging to the voice as a glob of stuff in the cords, making them unable to vibrate. Also difficult is "turning off" if you, the person, are "turned on." And the whole thing messes up your makeup.