how do you know there isn't a limit and its not gonna stop.. so that will make it so its NOT infinite

Scientists say that the universe will stop expanding when gravity becomes more powerful than whatever is causing the expansion, something they predict may never actually happen.

Another possibility is that the universe will keep expanding until all matter is infinitely dispersed.

But... Expanding where?

...whatever is outside the Universe. Infinite, complete nothingness, presumably.

Assuming that the Universe is "stuff", the Universe is expanding into the "not stuff".

That's impossible! Because if the universe holds all that exists, and outside him there is nothing. I mean, there isn't anything. We cannot say there is nothing. The form ``is´´ is not aplicable.
Or maybe our concept of the universe is very limited.

but what the fuck is outside of the universe. how does it expand if it doesn't have an end. fffffffuuuuu-

Outside the Universe, there is nothing. Not even quantum foam, or the fabric of empty space.
It isn't even "space" because there is no such thing as here or there outside the universe.
It's just nothing. An infinite nothing.

using the phrase "outside the universe" is rather misleading. there is no such thing as "outside the universe." it's not that there's nothing out there, it's that it simply doesn't exist.

so what would happen if you managed to enter that emptiness?

you can't. it doesn't exist.

the universe isn't expanding into anything, it's just increasing in volume, and decreasing in both density and temperature.

It wouldn't be possible to exit space in the first place.
Empty space can't have matter in it, matter can only exist where there is quantum foam.