Take a look here
Basically you need to call
CKEDITOR.instances.editor1.updateElement();
before running validation.
Just replace editor1
with the name of your textarea.
Then call
$(myformelement).validate();
EDIT
$("#my-form-submit-button").click(function(e){
e.preventDefault();
CKEDITOR.instances.event-body.updateElement();
$('#event').validate({
...options as above..
});o
})