I'm writing now based on my 40-years experience as a mental health counselor.

Neither of you can assume responsibility for this man's headaches and, much less so, for his emotional disstress.

Assuming Cluster without any evidence, history, etc. is not responsible. Even more so, is not regarding his talk of suicide as rather more important that the headaches.

First step is to ture to the local hospital and/or mental health agency to address his suicidial thoughts. These services are often low cost/free.

Medical care for his headaches is often free/low cost if you contact local health service agencies or social worker at the hospital.