I get strained badly and go to pieces (12)
I believe the answer is:
disintegrate
'go to pieces' is the definition.
(I've seen this before)
'i get strained badly' is the wordplay.
'badly' indicates anagramming the letters (letters in the wrong order).
'i'+'get'+'strained'='igetstrained'
'igetstrained' is an anagram of 'DISINTEGRATE'.
'and' acts as a link.
(Other definitions for disintegrate that I've seen before include "Fall apart - it isn't agreed (anag)" , "Lose all cohesion" , "Crumble" , "Smash" , "Decompose" .)