Same boat. What worked slowly with my mak was not arguing about whether mental health real, but just showing up functioning better after I got help. When she saw I was calmer, sleeping better, she came around a bit on her own. Also I stopped expecting her to be my therapist, that was the shift. I got actual support elsewhere and let her just be my mak. It's lonely at first but you build your own support system. Hang in there ya.