JQuery :: Validate Form - Check For Invalid Class Within Container

I'm running validation on a form that has two components, a payments segment and an address segment. Both of these need to be within the same form. By default, the address segment is hidden. Upon validation, I would like to display the payment segment, but only if there are validation errors within that segment. Using invalidHandler, I've been able to successfully fire a function when errors are returned, but I haven't found a way to check if there are errors within that container. My plan was to check for the invalid class within that container... something like this:

$(#formname).validate({
invalidHandler : function() {
if ($('.client_validation').length)
$('.billingAddress').addClass('showForm');
}}});
The problem is that the invalid class (.client_validation) isn't applied when the invalidHandler function is executed.