Simplify $y = \frac{1-2\exp(-x)\cos(x)+\exp(-2x)}{1+2\exp(-x)\sin(x)-\exp(-2x)}$

$$y=\frac{1-2e^{-x}\cos(x)+e^{-2x}}{1+2e^{-x}\sin(x)-e^{-2x}}\cdot\frac{e^x}{e^x}=\frac{e^x-2\cos(x)+e^{-x}}{e^x+2\sin(x)-e^{-x}}\cdot\frac{\frac{1}{2}}{\frac{1}{2}}$$ $$=\frac{\frac{e^x+e^{-x}}{2}-\cos(x)}{\frac{e^x-e^{-x}}{2}+\sin(x)}=\frac{\cosh(x)-\cos(x)}{\sinh(x)+\sin(x)}$$

After coreyman317's answer and your comment about large values of $x$, you could notice that for $x >24$ $$\frac{\cosh(x)-\cos(x)}{\sinh(x)+\sin(x)} \sim \coth(x)$$ for an error $ < 10^{-10}$.

Moreover, for large $x$, $\coth(x)\sim 1+2e^{-2x}$.