I wrote a snippet for someone a while back. It wraps without truncating words. While it doesn't help you preserve $1 (which you could do by copying $1 into a different variable), I thought you might find it useful.

sub line_wrap {
   my ($str, $max) = @_;

   my @lines;

   foreach my $line (split($\, $str))
   {
      # # Collapse spaces and tabs.
      # s/\s+/ /g;

      while (length($line) > $max)
      {
         my $max2 = $max - 1;
         if ($line =~ s/^(.{0,$max2}\S)\s+//s)
         {  # Break at space.
            push(@lines, $1);
         }
         else
         {  # No space.
            $line =~ s/^(.{$max})//s;
            push(@lines, $1);
         }
      }

      push(@lines, $line);
   }

   return join($\, @lines) . $\;
}
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Known Bugs: Counts tabs as one char, and only does line breaks at a space.