Send Message on Comment

if someone is interested i got it working:

function add_private_msg( $comment_ID, $comment_approved ) {
	if( 1 === $comment_approved ){
		$admin_user = get_field('admin_user','options'); // "dummy" user ID with site logo in avatar etc, i did set it in Advanced Custom Fields, you can store this ID in another way and get it also in whatever way you want. This will be user sending message, you can set comment author here if you want.
		$comment_id = get_comment( $comment_ID ); 
		$postdata = get_post($comment_id->comment_post_ID);
		if($postdata->post_author!=$comment_id->user_id) { //check if comment author is not post author (would be stupid to send msg about new comment to yourself :D
			  $message['message_to_id'] = $postdata->post_author;
			  $message['message_title'] = 'New comment';
			  $message['message_content'] = 'You have new comment in <a href="'.get_comment_link($comment_id).'">'.$postdata->post_title.'</a>';
			
				$override = array (
					'post_author' => $admin_user['ID'] // depending on how you got sender ID, you might need to set this var differently
					);
			  $x = fep_send_message($message, $override );
  //send msg from $admin_user to $postdata->post_author about $postdata->ID
		}
	}
}
add_action( 'comment_post', 'add_private_msg', 10, 2 );