<?php
        if ( isset($_POST['envia']) && $_POST['envia'] == 'ok' ) {
        $post = $_POST;
                $result = file_get_contents( 'https://www.google.com/recaptcha/api/siteverify', false, stream_context_create( array(
                        'http' => array(
                                'header'  => "Content-type: application/x-www-form-urlencoded\r\n",
                                'method'  => 'POST',
                                'content' => http_build_query( array(
                                        'response' => $_POST['g-recaptcha-response'],
                                        'secret' => 'secret_key'
                                ) ),
                        ),
                ) ) );
                $result = json_decode($result);
                var_dump( $result->success );
                // if everything's okay use your $post
        }
?>