Jeremy Corbyn apologises for hosting 2010 Holocaust event per BBC News

The headline story on the BBC this morning is this https://www.bbc.co.uk/news/uk-politics-45027582 that:

'Labour's Jeremy Corbyn has apologised for appearing on platforms with people whose views he "completely rejects".

Mr Corbyn's statement was in response to the Times reporting that he hosted an event in 2010 at which a Holocaust survivor compared Israel to Nazism.

Hajo Meyer's House of Commons talk was entitled 'The Misuse of the Holocaust for Political Purposes'.'

I'm pretty sure that I have read over the last few months that Jeremy Corbyn has always stood up against antisemitism when he encounters it. 

Some questions:

Did Jeremy Corbyn stand up against antisemitic sentiments in 2010 or didn't he then consider such sentiments antisemitic? 

If the sentiments expressed in 2010 weren't considered antisemitic by Jeremy Corbyn then, would they be now? 

Has Jeremy Corbyn's definition of antisemitism changed between 2010 when he was a Labour backbencher and now when he's Labour Party leader? 

Would expressing such sentiments in 2018 fall foul of the IHRA definition of antisemitism? 

Would expressing such sentiments in 2018 fall foul of the Labour Party's altered definition of antisemitism? 

How will Jeremy Corbyn survive this revelation or will he be replaced as Labour leader by the equally nasty John 'kneecaping' Mcdonnell?