"and another man sleeps with her." This sentence can be written as part of the previous sentence. This explains how she sinned against her husband. This is something that could possibly happen. Yahweh is telling Moses what to do if it does happen. (See: [[rc://en/ta/man/translate/figs-hypo]])
These phrases can be stated in active form. AT: "she has defiled herself ... his wife has defiled herself ... his wife has not defiled herself" (See: [[rc://en/ta/man/translate/figs-activepassive]])
# in the act
This refers to the act of adultery. The full meaning of this statement can be made explicit. AT: "in the act of adultery" or "sleeping with him" (See: [[rc://en/ta/man/translate/figs-explicit]])