Any judge with experience will have seen this pattern before (abusive, addicted spouse professes to have magically turned a new leaf and will now make things right for the child).
YOU know the truth and you have documented it, lived it, and can testify to the 5+ years of cr-p. The judge will see that. Be strong, tell the truth, and continue to take care of yourself and your son. You are doing an amazing job in an amazingly difficult situation.