Sad picture indeed,
Are these frames hollow or foam filled? Either way I think I'd have a go at repairing it. The curves in the shape lend themselves perfectly for a composite repair. And the seat tower appears to be located OK by the bits that are still attached.
After some judicious grinding and sanding, fill in with foam, lay up with carbon and/or glass fibre and it'll be stronger than new and only in need of a decent finish. Surfboards have been made and repaired this way for donkeys years. And there's plenty of options to prevent it from failing again.
Enjoy!