Last week all 28 leaders of the EU were holed up in buildings in Brussels for hours into the night, trying to strike a deal that would keep the United Kingdom in the European Union. The British people will have their say on what they came up with in a referendum in June. If they vote to leave the EU what will it mean, for the UK and for Europe more widely? Sarah Montague is in Brussels to talk to Martin Schulz, President of the European Parliament. Could Britain’s vote tear the whole Union apart?