Does samsara exist or not exists? Does samsara exist? Or does samsara not exists and it just looks to us that it exists, but in reality it is all the same "thing"?

Here's the updated question, to make it clearer:

UPDATE

Nibanna is the cessation of all that is conditioned, i.e. samsara.

As I understand it, when you attain Nibanna which is unconditioned, then you are out of samsara.

Does this mean, that when you attain Nibanna, samsara:


does not exist but it exists for other beings in samsara?
does not exist, and neither it exists for the other beings in samsara, because Nibanna is unconditioned, so there is no samsara, and consequently there are no beings?


Which one is it? 1 or 2?
The traditional Mahayana formula is that "Samsara is Nirvana". This is explained in depth in Madhyamaka literature. Here is one quote from Jay Garfield commentary on his translation of Nagarjuna's Mulamadhyamakakarika:


  It is [possible] to grasp after nirvana – to reify it as a state and to crave it as a phenomenon inherently different from samsara and as highly desirable since it is indeed characterized as liberation from suffering. But this grasping onto the end of grasping is itself a grasping and so precludes the attainment of nirvana. Nirvana requires, according to Nagarjuna, a complete cessation of grasping, including that onto nirvana itself. While that might seem paradoxical, it is not: To grasp onto something in this sense requires, inter alia, that one reify it. By refusing to reify liberation, in virtue of seeing it as the correlative of bondage, which itself is not inherently existent, it is possible to pursue the path to liberation without creating at the same time a huge obstacle on that path – the root delusion with regard to nirvana itself.


And from Master Dogen's Genjokoan:


  When everything is buddha-dharma, there are Samsara and Nirvana, Path, birth and death, Buddhas and sentient beings. When myriad things are without self, there is no Samsara, no Nirvana, no Buddha, no sentient beings, no birth and no death.