The problem with this situation is that no adult can be treated against their will unless they are homicidal or suicidal. If you think he is dangerous or may harm you then you have to call the appropriate authorities and have him taken to a nearby hospital. He will be admitted at that time. This is usually the best option because people treating him at the hospital will get an accurate picture of him. Do not feel guilty in facilitating this. He needs to be treated. This of course will be against his judgment and his opinion won't matter. If you continue this situation as it is you are faced with his dangerous decisions. And you don't know if he is taking his medication. I would unfortunately ask him to leave if he does not meet the criteria for inpatient and won't keep appointments for outpatient.
If this is helpful press accept