Synonyms for Lose one's composure:

• v.

  •flip out (verb)
  • blow one's stack,
  • lose one's temper,
  • go crazy,
  • wig out,
  • lose one's mind,
  • hit the ceiling,
  • crack up.
  •freak out (verb)
  • flip one's lid,
  • come unglued,
  • break down,
  • go bananas,
  • work oneself up,
  • lose one's cool.

• Other synonyms:

  •freak out
  • breaking down.