Hi there ~
I understand your concerns. Since your ex-partner is dependent on whatever medication or substance that you mention it would be best for him to be seen by a substance abuse
counselor. I advise you to contact your local community resources, and have a social services person assess his home situation. I believe if he is unfit to take care of himself and causing himself bodily harm that may lead to death is not taken care of by medical personnel, he may have to be taken to a treatment facility involuntarily. Having social services assess this situation and have a court order treatment would be the first thing you need to do. I believe that he may require a lot of therapy and visits with psychiatrists to detox himself off of all the substances he is on. Wish you all the best.
I hope this helps. Take care and have a lovely day!