This notion that athletes can't cry or show a little emotion is toxic. That's how mental disorders are formed. There's nothing wrong with crying or letting yourself get overwhelmed once in a while. It's healthy to process those feelings so you don't have to deal with it in the heat of the moment.
You can't tell someone how to process pain. It's literally something that can't be controlled. Even so, people shouldn't be judged for crying anyway. There's nothing wrong with it!