Rhombus $ABCD$ has side length $2$ and $\angle B = 120^\circ$. Region $R$ consists of all points inside the rhombus that are closer to vertex $B$ than any of the other three vertices. The area of region $R$ is given in the form \(\frac{k\sqrt{m}}{n}\). Please find the value of \(k + m + n\).

Let's think step by step and output the final answer within \boxed{}.
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