Zend Framework 3 Ajax Form Validation - contact form

I would like to present to you my code vision of Ajax form validation in Zend Framework 3. I am a beginner in Zend Framework and jQuery too, so I don't know that my solution is good and acceptable.

My module has simple work to do. A guest fills the contact form, presses submit button and form is processing. If a guest has enable JavaScript a request is processing by $.ajax().

contact.phtml (only jQuery script, the rest is not necessary)

<script type="text/javascript">
    $(function(){
        $("#foo").submit(function(event){
            event.preventDefault();

            $.ajax({
                url: '/kontakt',
                type: 'POST',
                dataType: 'json',
                data: ($("#foo").serialize()),
                success: function (data) {
                    console.log(data);

                    if (data.status == false) {
                        $(".form-error").empty();
                        $.each(data.msg, function (key, value) {
                            $.each(value, function (k, val) {

                                $(".form-error." + key).append(("<li>" + val + "</li>"))
                            });
                        });
                    }
                    if (data.status == true)
                    {
                        $(".form-error").empty();
                        $( "#contact-form" ).fadeOut( "1000", function() {
                            $(".description.form").html("<div class='form-flash-msg'>" + data.msg + "</div>");
                            $( ".description.form" ).animate({

                                opacity: 0
                            }, 10000 );
                        });
                    }


                },
                error: function (data) {
                    console.log(data);

                }
            });
        })
    })
</script>

Request has been sent so let's look what we have in ContactController->contactAction()`.

//ControllerContact->contactAction();



public function contactAction()
    {
        $contactService = $this->contactService;      //set by ContactController::construct()
        $form = $this->form;                          //set by ContactController::construct()
        $request = $this->getRequest();
        $response = $this->getResponse();
        $prg = $this->prg("kontakt", true);           // "kontakt" is a route name
        $vm = new ViewModel(['form' => $this->form]); //default ViewModel Object

        if ($prg instanceof Response)                 //PostRedirectGet plugin prevent
        {                                             //double form sending when someone refresh
            return $prg;
        }

        if ($prg === false) {
            return $vm;
        }


        $form->setInputFilter(new ContactFormFilter());  //InputFilter for ContactForm
        $form->setData($prg);                            //sets sent data

        if (!$form->isValid())
        {
            if ($request->isXmlHttpRequest())            //
            {
                $contactService->setResponse('status', false);
                $contactService->setResponse('msg', $form->getMessages());

                $response->setContent(Json::encode($contactService->getResponse()));
                return $response;
            }

            else                                      //If reguest is't xmlHttpRequest
                return $vm;
        }

        //Ok a form looks valid, let's try to send a mail

        $contactService->setResponse('msg', 'Dziękujemy - Twoje zapytanie zostało wysłane.'); //Default msg to return in view if mail will sent ofc.

        try {
            $contactService->sendMail($form->getInputFilter());
        }catch (\Exception $e)
        {
            $contactService->setResponse('msg', $e->getMessage()); //If we have exception, get exception message
        }

            if ($request->isXmlHttpRequest())                       //XmlHttpResponse request
            {
                $contactService->setResponse('status', true);
                $response->setContent(Json::encode($contactService->getResponse()));

                return $response;
            }

            else                                                    //Not XmlHttpResponse
            {
                $vm->setVariable('msg', $contactService->getResponse('msg'));
                $vm->setTemplate("contact/contact/form_sent.phtml");
                return $vm;
            }
    }

The last one is the ContactService class (it's short so I put the whole thing).

ContactService -> class

namespace Contact\Service;

use Zend\Mail;

class ContactService
{
    private $reciverAddress = '[email protected]';

    private $reciverName = 'ReciverName:)';

    private  $response = [];

    /**
     * @return mixed
     */
    public function getResponse($value = null)
    {
        if ($value == null)
            return $this->response;
        else
            return $this->response[$value];
    }

    public function sendMail($email)
    {
        $mail = new Mail\Message();
        $mail->setBody($email->getValue('message'));
        $mail->setFrom($email->getValue('email'), $email->getValue('personal'));
        $mail->addTo($this->reciverAddress, $this->reciverName);
        $mail->setSubject($email->getValue('subject'));

        $transport = new Mail\Transport\Sendmail();

        $transport->send($mail);
    }

    public function setResponse($key, $value)
    {
        if (empty($key))
            return false;

        $this->response[$key] = $value;
    }
}

Everything seems to be fine because it works but I think that maybe it can be done better. Is that even a safe use?