  Inertial effects in nonlinear magnetic reconnection are studied within the
context of 2D electron magnetohydrodynamics (EMHD) with resistive and viscous
dissipation. Families of nonlinear solutions for relevant current sheet
parameters are predicted and confirmed numerically in all regimes of interest.
Electron inertia becomes important for current sheet thicknesses $\delta$ below
the inertial length $d_{e}$. In this case, in the absence of electron
viscosity, the sheet thickness experiences a nonlinear collapse. Viscosity
regularizes solutions at small scales. Transition from resistive to viscous
regimes shows a nontrivial dependence on resistivity and viscosity, featuring a
hysteresis bifurcation. In all accessible regimes, the nonlinear reconnection
rate is found to be explicitly independent of the electron inertia and
dissipation coefficients.
