How do you output custom code between posts in the loop?

I am trying to put a header before past posts and after future posts.

I’m using get_posts() in a function to output the posts using a foreach loop for a custom post type ordered by date (meta key). If a post’s associated date is less than the current date (i.e., dates not in the future), I want to output some HTML.
if ($custom_post_date >= $today && $index === 1)
The problem I am running into is that the HTML gets output after the first post that is in the past. How can I output the HTML before the first post that meets the criteria? Is there a way to go back in the foreach loop or something to that effect?