  The intrinsic frustrated nature of a kagome lattice is amenable to the
realization of exotic phases of matter, such as quantum spin liquids or spin
ices, and more recently the multiple-$\mathrm{\textbf{q}}$ charge density waves
(CDW) in the kagome metals. Despite intense efforts to understand the mechanism
driving the electronic modulations, its origin is still unknown and hindered by
competing interactions and intertwined orders. Here, we identify a
dimerization-driven 2D hexagonal charge-diffuse precursor in the
antiferromagnetic kagome metal FeGe and demonstrate that the fraction of
dimerized/undimerized states is the relevant order parameter of the
multiple-$\mathrm{\textbf{q}}$ CDW of a continuous phase transition. The
pretransitional charge fluctuations with propagation vector
$\mathrm{\textbf{q}=\textbf{q}_M}$ at T$_{\mathrm{CDW}}$$<$T$<$T$^*$(125 K) are
anisotropic, hence holding a quasi-long-range bond-orientational order. The
broken translational symmetry emerges from the anisotropic diffuse precursor,
akin to the Ising scenario of antiferromagnetic triangular lattices. The
temperature and momentum dependence of the critical scattering show parallels
to the stacked hexatic $\mathrm{B}$-phases reported in liquid crystals and
transient states of CDWs and highlight the key role of the topological
defect-mediated melting of the CDW in FeGe.
