これが私の見解です
$text = "Lorem ipsum dolor sit amet, consectetur adipiscing elit. Sed ornare tincidunt euismod. Pellentesque sodales elementum tortor posuere mollis. Curabitur in sem eu urna commodo vulputate.\nVivamus libero velit, auctor accumsan commodo vel, blandit nec turpis. Sed nec dui sit amet velit interdum tincidunt.";
// Break apart at new lines.
$pieces = explode("\n", $text);
// Use reference to be able to modify each piece.
foreach ($pieces as &$piece)
{
$piece = wordwrap($piece, 80);
}
// Join the pieces together back into one line.
$wrapped_lines = join(' ', $pieces);
// Convert new lines \n to <br>.
$wrapped_lines = nl2br($wrapped_lines);
echo $wrapped_lines;
/* Output:
Lorem ipsum dolor sit amet, consectetur adipiscing elit. Sed ornare tincidunt<br />
euismod. Pellentesque sodales elementum tortor posuere mollis. Curabitur in sem<br />
eu urna commodo vulputate. Vivamus libero velit, auctor accumsan commodo vel, blandit nec turpis. Sed nec<br />
*/