Botched up /etc/network/if-pre-up.d/iptables, now can't boot

I was following this guide to get my iptables to restore on reboot, but messed up somehow: https://wiki.debian.org/iptables

Now, when I boot I get this error: http://snag.gy/yXAt7.jpg

Any guides or step I can follow to get booted up so I can work on the file and hopefully fix my mess?

Thanks for the help!