Former BEATLE Sir Paul McCartney has opened up about his marriage breakdown, reportedly telling party-goers in London this weekend (23-24SEP06), "It's been the most terrible time." The singer attended a reception thrown by daughter STELLA's husband ALASDHAIR WILLIS, and guests reveal he appeared emotional when probed about his failed relationship with Heather Mills. One tells British newspaper the Daily Mirror, "As soon as the subject of Heather came up, his demeanour totally changed. "He started shaking and there were tears welling up in his eyes." The newspaper reports MCCartney told another guest, "Having to come to terms with this! It's been so horrible, so horrible. "I don't know how to deal with it at all. I just cannot talk about it." MCCartney and Mills separated in May (06) and are currently in the process of getting a divorce.