Very close! Nice work. If you adjust it just a bit, it will be perfect.
Our friendship was put to an end when I noticed that you were no different from those bastards we've hated.
The words, 'it's where' is not needed because you already have when in the sentence that shows the meaning/context. You want to use different because you are describing so you need the adjective, not the noun (difference is a noun). You need an s on bastard because you said those, which is more than one.
Good luck!