At this point, you probably don't need it for this particular beer anymore. Just clean up the existing tube and put it back on there.
Going forward, you could take the rubber grommet out of the bucket lid, drill to enlarge the hole in the bucket lid to accomodate a drilled bung, then use a 3/8" tube in the drilled bung going forward.
That, or just spend $20 and get a 6 gallon better bottle!