insane? this movie doesnt have an end, you dont know if he is insane or sane.

He IS insane. All the clues are there, almost right from the start. You can't really argue that he WASN'T, that just means that you didn't get the movie in the first place (I suggest you rewatch it).

Consider this, Laeddis was having strange dreams/hallucinations before he was given anything from the doctor and others (aspirine, cigarettes, whatever). All the memories you see Laeddis having throughout the movie are real, there is no way the people working there would have "implanted" those memories (plus, this ain't a sci-fi).

Consider other clues, "Teddy" was having a band-aid on his forehead most of the movie, giving a hint what has happened to him before, the anagrams of all the names of the characters he has made up, the shrink (acting as a "marshal") fumbling with the gun at the gate at the beginning, and so on. His hallucinations are of his own doing, the doctors at the facility are not doing this to him. Salando and the scene in the cave was all in his mind. The storm was a manifestation of Teddy's fear for water, which comes from the scene where he finds his children murdered (this event real, as well as that he murdered his wife). Another clue to this is, after the storm when he is sitting at the stairs, all the trees and everything that was wrecked during the storm, is suddenly back to normal. It was not real. He is a patient on the island, he is insane right from the start.

The doctor and his shrink also explains it to him at the end in the lighthouse, a scene which judging by the characters, is no doubt telling the truth to Laeddis. It is also explained that they made it all up ("role play"), in order to try to snap Laeddis back to normality for good (which was tried 9 months earlier, but Teddy "reset" back into his cycle of insanity).

Also consider the ending, which is conclusive, not without an end, as you claim; At the end he is talking to his shrink, which asks Laeddis "now what?". In which he replies, "This place makes me wonder, is it better to live as a monster or die a good man?" Laeddis has realized who he is at the end, but he walks willingly to the lobotomy because he has decided it's better to "die" a good man - he don't want to live as the monster Laeddis, in which he feels responsible for the death of his wife, as well as his children (because he was unable to find help for his wife). The lobotomy is a way of erasing the guilt for good.