Are there multiple realities in Re:Zero, or is it just one reality rewinding? For example, in one timeline Subaru kind of screws up- Rem dies and Ram is furious at him and tries to kill him. He ends his life in that timeline by jumping off the cliff, committing suicide. This left me wondering "how would the people from that life continue to live?" Or rather, does that world continue?
Warning, spoiler-heavy answer.

There is break-down of most chapters of light-novel (numerous spoilers inside). According to summary of Arc 4,


   author gives a hint, that each timeline, where Subaru dies, may exist even after his death, at least, some events in some timelines are described.