This man dug a pond right by the biggest I think pine tree I have ever seen. So obviously he hacked up her roots and it’s so so sad because now the tree is half dead! Is there anything I can do to save this huge tree?
No, there's nothing to be done, except possibly to ensure it's well watered during any extended period of hot, dry weather if it's still alive. The tree will either survive or it won't, but you should keep a check on it - if it dies, just make sure there's no risk of its falling on property or people.