So you are helping your son, checking his assignments, and he is not handing his assignments in. And you missed that part.
Let's for a minute ignore all the rest of your post.
You don't accompany your son to school nor homeschool him. I'm assuming your son is not 3 or 4. He attends school, after having received help and support from his family, and doesn't turn in his completed work. This is something your son needs help with, not something that makes you an incompetent idiot. Your son needs a plan that works for him.
I suggested recently in another post that a mom help her child devise a system so that completed work gets turned in without being forgotten or overlooked. Post-It flags (those little sticky things that stick out past the edge of the page) in a bright color, applied the night before to completed homework, helps a kid remember to turn work in. If he sees the flag sticking out, it reminds him that there's something that's not turned in. If all the flagged pages are gone at the end of the day, everything is turned in. That night, put new flags on completed homework. Something like that might help your son. It might be a different system that you work out, whatever makes sense to him: a checklist, etc.
If one forgetful child, who receives help in a safe and loving home, who is independent at school but neglectful of homework, makes you an incompetent idiot in your eyes and in the eyes of your husband, well, then I need a thesaurus to come up with new words to describe the depths of my idiot-ness.