My ex-husband has a 20+ year history of alcohol and drug abuse, sex with prostitutes during our marriage, Bipolar Disorder, domestic violence and emotional abuse of the kids...He's filed a Modif. so he can get unsup. visitation and shown he's clean & taking meds. How likely is he to get unsupervised visitation when he was noncompliant for almost 3 years of the court order for testing AND admitted blatant deception throughout divorce proceedings (lying to judges, custody evaluator, etc.)? I have no S/A or M.I. history & been taking care of kids very well for nearly 3 years.
Mr. Havens is correct that the Court will consider your ex-husband's more recent behavior as a material change in circumstances IF his behavior is different and better. The real question is who is he NOW? Is he still emotionally unstable? Does he still present a threat to the child? What is the relationship between the child and the Dad now? You didn't say whether or not the Dad has followed the order recently or how the supervised visitation is going - that is very relevant to whether or not he gets unsupervised access. In these cases, the Judge will heavily consider the reports from the visitation supervisor also.
Speaking to a lawyer could help you determine what is best for the child now.
If your exhusband can show an extended period of good behavior, then the Court may be inclined to permit his unsupervised visitation. The Court's primary interest is the best interests of the children. Accordingly, a judge should not test the waters so to speak to see how it goes. Rather, your exhusband will need to prove to the Court that he has cleaned himself up. Even then, the Court may (and you should ask for) require urine testing and that the visits be short (i.e. not overnight).
You should consult with an attorney as soon as possible.