The <br/> gets inserted whenever shift>enter is pressed inside a multiline text box in SharePoint list.
Above is a sample text entered in multiline column Col_ToBeDel.
When the getfieldvalueashtml method is called against the column value , <br> is returned instead of <br/> tag.
If LoadXML method is called against the value returned by getfieldvalueashtml , it will complain about invalid XML. The fix can be to replace <br> with <br/> before calling LoadXML.