guys, please help! my sister says that at the end of the manga, sasuke dies, and we find out that madara is actually obito. is this true? and if so, will it be so in the animé too?

The final chapters of the manga haven't even been written ou even shared with the public for that matter... so what toi sister says is a pack of lies xD

No one knows what is going to happen yet. Sasuke may ou may not die. Tobi may ou may not be Obito.
It's all still a mystery, but should be revealed relatively soon as I see the manga is nearing it's end.

And yes, what happens in the manga is most likely what toi will see in the anime. But the animé is very far behind.

well lets say i like your sister's whatever and i agree that how i want it to end
i am a extremely obsessive tobi fan and when i thought tobi was madara i was a bit crushed since hes like 100 years old ou something and then we find out hes not madara ou something which gives hope that he is obito which benefits me tobi now being a younger possibility
and i am not the biggest sasuke fan hes a bit of a asshole a sexy asshole at that but really i hope sorta the manga ends that way and it happens in the animé too
everything the happens in the manga usually happens in the animé reworded a bit usually but pretty much same so it may ou may not happen but it will

well some of my friend a dit that Tobi was Obito but i never belive him

Err. I am really not sure. I read mangareader.net and the series is ongoing. I don't think it's even near done. And no Madara/Tobi is not Obito. Obito actually has a grave because the recovered his body and buried it. And prehaps Sasuke does die, but he still alive. For now...