The main thing in this sorry tale is the use of somebody else's insulin. Never ever use other people's prescription medicines, particularly insulin. Has it been correctly stored? You have no idea. Is it in date? Odds are, you didn't check. It's a legal nightmare if anything goes wrong - your friend is effectively prescribing a prescription only medication illegally, and would be responsible in law for any problems arising. I understand that this was done with the best intentions, but the road to hell is paved with good intentions.
Furthermore, as AJ said, Lantus lingers for longer than you might think, so when you restart the pump there is a danger of hypos.
You should always have Levemir and a short acting insulin in the fridge to use in such an emergency, but I'm rather taken with AJ's suggestion of using hourly short acting, with frequent testing. I did that one night away when I'd forgotten to pack my Lantus, and it worked rather nicely.