Is there an end to the universe?
Not that we know of.
Astro-physicists discuss at length the shape of the universe with some saying it is pancake flat while other contend it is spherical much like a soccer ball.
Then there is the suggestion that we are part of a multi-verse, that is just one of an infinite number of universes. In theoretical physics both possibilities exist and neither can be proven.
And just to blow your mind a little more: those same physicists will tell you that we sit at the center of the universe with almost all galaxies accelerating away from us. But, and this is the killer, if you lived in the Andromeda galaxy that statement would still hold true, you'd be at the center of the universe with all other galaxies accelerating away from you.
Astro-physics is a very large collection of theories most of which are not provable, at least with our present knowledge and mathematical formulae. I mention that because the math, particular with regards to gravity, that works to explain the visible universe does not work in the quantum universe, that is at the atomic level. The quest for the unified field.
No one knows and at least for the foreseeable future, no one will be able to figure it out.