How do I add recent posts to the menu?

How to add recents posts to the menu? Entries with pictures. Menu-item-object-custom items in a div container?

What I have now is: header.php

wp_nav_menu(
    array(
        'theme_location' = 'menu-1',
        'menu_id'        = 'primary-menu',
        'menu_class'     = 'display_lasts_ten_posts_for_categories_menu_item',
        'walker'         = new WPSE_78121_Sublevel_Walker,
        )
    );

functions.php

add_filter('wp_get_nav_menu_items','display_lasts_ten_posts_for_categories_menu_item',10,3);
function display_lasts_ten_posts_for_categories_menu_item( $items, $menu, $args ) {

$menu_order = count($items);
$child_items = array();

foreach ( $items as $item ) {
    if ( 'category' != $item-object || ('category' == $item-object  get_category_children($item-object_id)) )
        continue;
    $category_ten_last_posts = array(
        'numberposts' = 3,
        'cat' = $item-object_id,
        'orderby' = 'date',
        'order' = 'DESC',
        'meta_query'     = array(
            array(
                'key'     = 'wazny',
                'value'   = 0,
                'compare' = 'LIKE',
            ),
        ),
    );
    foreach ( get_posts( $category_ten_last_posts ) as $post ) {

        $post-menu_item_parent = $item-ID;
        $post-post_type = 'nav_menu_item';
        $post-object = 'custom';
        $post-type = 'custom';
        $post-menu_order = ++$menu_order;
        $post-title = $post-post_title;
        $post-url = get_permalink( $post-ID );
        $child_items[]= $post;

    }

}
return array_merge( $items, $child_items );
}


class WPSE_78121_Sublevel_Walker extends Walker_Nav_Menu
{
function start_lvl( $output, $depth = 0, $args = array() ) {
    $indent = str_repeat(\t, $depth);
    $output .= \n$indentul class='sub-menu'div class='sub-menu-wrap'\n;
}
function end_lvl( $output, $depth = 0, $args = array() ) {
    $indent = str_repeat(\t, $depth);
    $output .= $indent/div/ul\n;
}
}

I want to achieve this effect: