One of my big pet peeves is when a writer has their characters - usually female, but not always - cry at the drop of a hat. It feels like too easy a way to show emotion, especially when an entire scene is spent showing a character break down. Be aware that though it might not play so on the page - such extreme emotion can often feel overwrought on screen.
I once read a script where the female protagonist broke down in tears three times in the first act. That's a bit excessive, and I couldn't help but feel that on-screen she'd come off as a crybaby. I think it's more interesting to show a character trying NOT to cry. In real life, people try hard not to show their emotions like that for fear of seeming weak. The phrase "Jenny fights back a tear" always is more effective for me than, "Jenny's eyes fill with tears and she loudly sobs as she collapses to the floor."
Here's the thing - crying often looks awkward on screen. No one looks good when they cry and there are many actors who are TERRIBLE criers. Some scrunch their face too much, some have a hard time producing tears, and some have awkward things happen to their voices when they try to speak and cry.
If you are going to have your character suffer a breakdown like this, try to have it happen later in the script. This way, we've gotten a feel for that character's emotional range so that breakdown will mean something. It'll play as a chink in their armor. Even so, less is often more. An actor can convey a lot with body language and physical acting, so give them the chance. Maybe play them as more numb and stunned than truly overwrought. Or perhaps whatever upsets them causes them to tap into their anger, or take their frustrations out on someone or something near them.
Never write "They fall to the floor and sob" until you have exhausted every alternate possibility.
