The 'Rehab' singer "went ballistic" when she saw Blake Fielder-Civil
chatting intimately with super model Lily Cole, at the bash at London
department store Harvey Nichols.
Blake then left with Lily, leaving Amy alone at the party for three hours
before he returned to continue the argument.
A source said: "Blake and Lily were chatting very intently for ages before
Amy arrived.
"Amy went ballistic when she saw them together and dragged Blake to the
toilet to confront him. They were arguing for at least 20 minutes. Amy was
shouting at him and asking him what an earth he was doing with Lily.
"Blake tried to explain but Amy was having none of it. People waiting to use
the toilets were just standing their open mouthed. Their marriage is hanging
by a thread."
The tempestuous couple eventually sorted out their differences, but Amy is
said to be fuming about the attention Lily gave Blake.