I think six months is a very short time.
I am just so sorry and want you to find comfort so badly

The only thought I feel compelled to share, on the issue of feeling like a total failure, is that the child you created together is forever. He was here, not for as long as he should have been, but nothing can take back the fact of his existence. You did that, you and your dh, you created a beautiful boy. He was real and loved and he had a happy life. Once you are a mom, you can never NOT be a mom, that is forever.