UPDATE 5-PM Johnson says tempers need to calm after Brexit furore

* House of Commons at boiling point in raucous debate

* PM Johnson says Brexit will "lance the boil"

* PM had goaded opponents who scream "resign"

* Johnson defends his words on "surrender act"

* PM's sister condemns Johnson

* Cox's husband appeals for calm, warns over rhetoric (Updates with Johnson comments)

By Guy Faulconbridge and Elizabeth Piper

LONDON, Sept 26 (Reuters) - British Prime Minister Boris Johnson said on Thursday tempers needed to calm after a vitriolic session in parliament the day before, maintaining that only Brexit could resolve deep divisions among lawmakers and across the country.

Parliament reached boiling point on Wednesday when Johnson and his opponents engaged in hours of furious argument over Brexit, with lawmakers hurling allegations of betrayal and abuse of power across the chamber.

The anger had become so intense that the husband of a lawmaker murdered days before the 2016 EU referendum said it could encourage violence unless politicians toned down their rhetoric.

"We do need to bring people together and get this thing done," Johnson told BBC TV. "Tempers need to calm down and people need to come together because it is only by getting Brexit done that you will actually lance the boil of the current anxiety."

The ferocity of the Brexit debate has shocked allies of a country that has prided itself as a confident - and mostly tolerant - pillar of Western economic and political stability.

However, three years since Britons voted to leave the bloc, the outcome remains mired in uncertainty with a supporters on both sides of the debate becoming increasingly entrenched.

UNLAWFUL

Johnson returned to the House of Commons on Wednesday after the Supreme Court ruled that his decision to suspend parliament earlier this month was unlawful.

He challenged his opponents either to bring down the government or get out of the way to allow him to deliver Brexit, something he has vowed to do by Oct. 31 whether of not he has agreed a withdrawal deal with the European Union.

His opponents roared "resign" and some cast him as a cheating dictator who should stand aside after the court ruling.

Johnson provoked anger by repeatedly calling a law that forces him to ask the EU for a three-month Brexit delay next month unless he can strike a deal as the "Surrender Bill".

His critics say such language is often used in threats of violence or worse received by lawmakers, particularly women.

Johnson defended his use of the term to supportive Conservative lawmakers on Thursday, arguing that the legislation would hurt Britain's negotiating stance with the EU.