Examples aren't proof. For one so (self-proclaimed to be) versed in philosophy, it's said that you don't realize it.
However, I grow tired of this, so I will offer a disproof.
1. Premise: Everything that is possible is necessarily true.
2. Premise: It is possible that p is true.
3. Premise: It is possible that ~p is true.
4. p is true (from 1 and 2).
5. ~p is true (from 1 and 3).
6. 4 and 5 are contradictory.
7. Either 1, 2, or 3 is false (from 6).
8. Neither 2 nor 3 can a priori be assumed false.
9. It is impossible to prove either 2 or 3 is a posteriori false.
10. 1 must be false (from 7, 8, and 9).
Pretty good for not having had any philosophy classes, don't you think?
Unicorns exist or they don't.
The same logic can be applied to something exists or nothing exists.
Unicorns exist or they don't.
Something exists or nothing exists.
Nothing cannot exist.
If nothing cannot exist then it is possible that unicorns can exist.
In another possible world unicorns exist.
If it is possible in another world that unicorns exist then it is necessarily true.
If something is necessarily true in another world then it is true.
If it is true that unicorns exist in another world then it becomes possible that they exist in this world because it is necessarily true in another world.
Does that prove that they exist in this universe. Who knows? In another possible universe they do exist because they can be imagined.
From the imagination, if something can be defined and given form then it becomes possible.
If something becomes possible then that possibility can be made manifest.
Is a square-triangle possible, no because it cannot be imagined. If it cannot be imagined then it is not possible.
If something is not possible then it becomes necessarily false. If it is false in this world then it is false in all other worlds.
If something is true then it can be made manifest. But if something is necessarily true then it becomes true; whether it be in this world or another possible world.
So if something is possible then it becomes necessarily true and if it is necessarily true then it becomes true in another possible world.
Is it possible that a world can exist within a world?
The universe is a microcosim of existence. Worlds living side by side. If one can imagine that a universe exists within a universe then it is possible that an infinite number of universes exist all in one universe, 'side by side.' Therefore all universes are one. In another universe if it is necessarily true that unicorns exist then logic dictates that unicorns exist in this universe if all other universes exist in one universe.
Wow man blows the mind apart. It's like a crazy acid trip. And yes I did lots of acid when I was a kid. Digest that. Think of the infinite possibilities and enchanted kingdoms.