This looks like JSON embeded in XML CDATA.
You will first have to extract the CDATA; see this: <
http://www.soapui.org/Functional-Testing/working-with-cdata.html>. The result of that you will have to parse as JSON, with something like JsonSlurper() - Google for some tutorials if need be.
As a side note, this is pretty poor design. You might want to have a talk with your lead(?) developer to reconsider. See <
http://www.xml.com/pub/a/2003/08/20/embedded.html> for some thoughts.