@Royce

I think this is better, since you can still use the ampersand in your text:

<?php
function HtmlEntitySafeSplit($html,$size,$delim)
{
  $pos=0;
  for($i=0;$i<strlen($html);$i++)
  {
    if($pos >= $size && !$unsafe)
    {
      $out.=$delim;
      $unsafe=0;
      $pos=0;
    }
    $c=substr($html,$i,1);
    if($c == "&")
      $unsafe=1;
    elseif($c == ";")
      $unsafe=0;
    elseif($c == " ")
      $unsafe=0;
    $out.=$c;
    $pos++;
  }
  return $out;
}
?>