To quote Alonzo (Denzel Washington) in training day:
If you go for the cruelty waiver, you have to prove it. This is nothing new.
As possibly ridiculous as that sounds - & being contrary to - in the age of 'believe all victims', and when combined with the fact that many forms of abuse are not even really documentable as they aren't physical (believe me, I can attest to this), it remains the case with regards to immigration law and USCIS policy.
You were denied as a result of not providing documents proving this, and not producing what they asked for with the RFE.
Now, what constitutes 'proof' is entirely subjective of course.., but proving someone is a terrible spouse does not prove they were abusive.
Would suggest you get rid of that lawyer too, if they did not give you correct information regarding the RFE or follow your instructions in response to it.