The Collaborative International Dictionary of English v.0.48:

Heartbroken \Heart"bro`ken\ (-br[=o]`k'n), a.
   Overcome by crushing sorrow; deeply grieved.
   [1913 Webster]

WordNet (r) 3.0 (2006):

heartbroken
    adj 1: full of sorrow [syn: brokenhearted, heartbroken,
           heartsick]

Moby Thesaurus II by Grady Ward, 1.0:

32 Moby Thesaurus words for "heartbroken":
   broken-down, brokenhearted, crestfallen, crushed, cut up, dejected,
   depressed, desolated, despondent, disappointed, disconsolate,
   disheartened, dispirited, distressed, doleful, downhearted,
   grief-stricken, heart-stricken, heart-struck, heartsick, inundated,
   miserable, morose, mournful, overcome, overwhelmed, sorrowful,
   stricken, undone, unhappy, upset, woebegone