Tilt the barrel so the leak is uppermost, and you will lose pressure but not ale. In the process you might find that it is an excess of pressure that is causing the leak to be significant. With luck you should be able to keep the ale in good condition overnight while you spend Monday buying a new barrel. Then add a spoonful of sugar to start fermentation again and put some life back into the product.
Do please stay sober enough to let us all know how you get on …
Tim