That depends, what's the nature of the brain injury, or do you not even know that? The current diagnosis is more relevant than the old diagnosis to getting some safety assurances put into place. Does your daughter need to spend time with her dad to put her mind at rest, even if he is a messed up jerk? Do you usually drive her to and from visitation? Regardless of whether you need something done right away, or long term changes to the visitation, basically you need to call your lawyer or legal aid. If you're not going to get any cooperation or information from your ex or his wife, I don't see any other alternative.