I'm not sure where to begin. Your lack of self worth saddens me. Unless its directly addressed, I only see you further enabling the poor behavior of those around you.
Your husband and his mother (and who knows who else) walk all over you. You tolerate, make excuses for and enable their abuse. Then, you self abuse by calling yourself "the biggest idiot in the world". Why is this? I think you need a very good IC to help you learn to love and respect yourself more.
In direct response to your post- your husband's excuse is mind bogglingly stupid. One would have to be an even bigger idiot to accept such an excuse. Do not be that idiot- you are not "the biggest idiot in the world".
