make the most of something - to use a situation or object to be benificial (positive) instead of negative
to break a sweat- to start sweating
to freak out- to be very emotional (can be happy, sad, excited, scared etc.)
to split- in this context "split" means to leave quickly
it just don't fit- something is not right
ex- colloquial way to say "ex-girlfriend" or "ex-wife"
background check- an official check done to uncover information in someone's past
come to this- to end up this way (implies negative situation and limited options to fix the situation)