Suz - I know how difficult it is to not feel guilty about things that happen to our children but hindsight is 20/20. You are both loving parents who wanted the best for your child and have done everything you could to the best of your ability at the time that you did it. Did you make mistakes? Absolutely, but they weren't mistakes to intentionally harm your child - either physically or emotionally. You only ever wanted to help him. If that help was sometimes misguided that only proves you are humans who make mistakes with the best of intentions.
Go easy on yourselves. You have done your best and I know that you will continue to do so - we get better as we learn from the mistakes that we make.