need to save html in a metabox, problem with add_post_meta

Hi,

When saving meta data with a custom metabox add_post_meta() is stripping out double quotes and the closing ‘/’ for the closing tag.

I need to be able to save this:
<meta name="fb:whatever" content="somecontent"/>

How do I protect the string so add_post_meta() won’t strip it?
I tried addslashes() but that ends up causing an error somewhere and stoping it from writing anything to the database at all.

here is my save code excluding the admin check part.

$current_data = esc_textarea(get_post_meta($post_id, '_my_meta_facebook', TRUE)); 

    $new_data = $_POST['_my_meta_facebook'];

    //$new_data = addslashes($new_data);
    //my_meta_facebook_clean($new_data);

    if ($current_data)
    {
        if (is_null($new_data)) delete_post_meta($post_id,'_my_meta_facebook');
        else update_post_meta($post_id,'_my_meta_facebook',addslashes($new_data));
    }
    elseif (!is_null($new_data))
    {
        add_post_meta($post_id,'_my_meta_facebook', addslashes($new_data), TRUE);
    }

    return $post_id;

Thanks