2D crack problem

When using CZM for crack propagation, for each CZM element, once the separation delta > delta_c, the adhesive is completely damaged, cannot transmit stress. delta_c is the separation on the right side of the bilinear or trapezoidal models. How can I get the length of the crack for each increment of applied displacement or load? I can see that the totally damage element disappear from the Visualization but I need a better way that gives me crack length, not just a picture that shows the crack longer for each increment.