Ditto @DoWhileNot. Let me add: Copyright law very specifically says that you cannot copyright IDEAS, you can only copyright the words used to express an idea. Unless you copy someone else's exact words, you will not be found guilty of copyright violation.
I hear this question a lot from both sides: people afraid that they can get in trouble because their book is somehow similar to another book, and people asking if they can sue for copyright violation because someone else wrote a book similar to theirs. Often the similarities are so general that if you think about it, if there was really a law against it 90% of the books ever printed would be illegal. Like, "I wrote a book about two people falling in love and now I see that somebody else wrote a book about two people falling in love." There are thousands, probably millions, of such books. No, it's not a problem.
You might justifiably be worried that the existence of a book that is in some ways similar to yours will hurt your sales, because people will buy that one instead of yours. But there's no copyright issue. Not having read either book, I can't say if this is a problem here. And in any case, unless the other book is very well-known, odds are most of your potential readers will never have heard of it.