Removing comments from a WXR export

I have a 275 MB WXR file that is chock-full of SPAM comments (almost 70,000). I need to remove the comments so I can import the WXR via WP-CLI.

I've tried importing with the comments included but it times out, and my host has tried increasing my PHP timeout to something ridiculous. So the comments have to go.

I've also tried opening the WXR using Sequel Pro on my Mac but nothing happens. Again, I think is because of sheer size of the file.