How to deal with collapsing back an expanded long comment?

When you have a site that has practically no limit on the comment length, and you inevitably get very long comments, you obviously have to crop them by default in order to keep the page neat, and then only expand them when users click to Read more.

But if that Read more button then turns into a button that collapses the comment back, this means you still have to go through scrolling the entire length of the full comment, which can be humongous (for context, the longest comment in my database has ~58k characters), and then you're screwed if you don't want to finish the comment, because navigating either way is now very hard.

While putting the show/collapse button before the comment text feels super awkward to use.

What's the best way to deal with this?