What visa options do I have to stay in Thailand to care for my wife diagnosed with dementia?

Long story but looking for advice. I married my Thai wife in 1978. I’m retired and we live on my pension plus both of us receive social security benefits. My wife had a stroke 2 years ago. Not much physical damage but she has lost most of her ability to use and understand English. There is some loss of Thai language but after a year of struggling with communication (I speak very little Thai) she flew to Thailand to stay with her niece near Chaiyaphum. It allowed me to continue working as a contractor then I joined her in Thailand for 2 months in June this year. I returned to USA and went back to work with the plan for her to return home in October. When she got home I left work to stay home with her. She has now been diagnosed with dementia. Her agitation is somewhat controlled with medication but it’s getting worse. The doctor has recommended I start looking for a care facility but it would be impossible to find something here where she could communicate with caregivers plus they are really expensive. I’m looking for suggestions for visa for myself that would allow me to stay with her in Thailand as long as possible if I can find a suitable facility there. Thanks for any help.