Well I'm glad she's still ok with a leash as she probably received unfair corrections with it from that "trainer" but I meant I wouldn't even use a leash to do basic obedience with her. I would just use a bag full of treats and work on basic obedience (even if she already knows it) like sit down come stay heel etc to build her confidence in those areas again. Those basic commands could have been a source of torment with the "trainer" and now you need to make them a source of fun, bonding, confidence etc. I would have your husband do it as well.
The pottying in the house can also be from stress now taking into account the full situation. I personally wouldnt correct her. Just lead her outside being as nuetral as possible. I would start from scratch as if she were a little puppy again to try to rewire what that trainer scarred her with. But this is my personal opinion. Confidence building is a must. She needs to learn that she can obey and follow "rules". That everything doesnt have to result to corrections and abuse.
Mace vom Misteri, FO ~ GSD
Ryot ~GSD (my true heart dog RIP)
Apollo vom Deutschen Adler ~GSD (rehomed)