$xml = '<?xml version="1.0" encoding="UTF-8" standalone="no"?>
<article articleId="5859" lastModifiedById="13" metatype="Article" rootArticleId="4110" type="India">
<title><![CDATA[india]]></title>
<created>20070516T200000</created>
<lastmodified>20070606T092337</lastmodified>
<section type="Paragraph">
<title>india</title>
<asset type="HTML Multiline">
<description>Paragraph</description>
<data><![CDATA[<h1>INDIA</h1><p class="details">First Line<br/>Second Line</p>]]></data>
</asset>
</section>
</article>';

 $dom = new DOMDocument('1.0','utf-8');
 $dom->loadXML($xml);
  
  $sections = $dom->getElementsByTagName('section');
  foreach($sections as $section) {
    $xpath = new DomXPath($dom);
    $data = $section->getElementsByTagName('data');
    $dataElem = $data->item(0);

    $d = new DOMDocument();
    $d->loadHTML($dataElem->nodeValue);
    $xp = new DOMXPath($d);
    $details = $xp->query('//p[@class="details"]')->item(0)->textContent;
    var_dump($details);
    die();
 }

?>

Returns:
First LineSecond Line (the <br/> is removed.