Do you know anyone that suffers mental illness and they are in denial that they have it?

My ex has mental illness and sadly she is in denial , her personality switches like a light switch , her and I are still mutual for the kids’ sake and we are still friends’ She will be nice and kind and polite for awhile but then all of a sudden she turns into this miserable grumpy person and she starts saying negative things about everything to the point I don’t know who she is when she turns that way. When she snaps out of it , she is in complete denial about the things she said and acts like she never said the things she said. I feel bad for her but sadly her mental illness is too much for me to handle to the point I tell her she needs to get serious help, Her doctor has been adjusting her meds and when her meds work she turns back to a nice person with a good heart , she wants to get back together with me , but I tell her No, and tell her the reason why is because I can’t handle her episodes , because it leaves me with a constant question mark over my head. I still love and care about her , but I don’t love and care about her Dark side. Am I wrong to not give her another chance?
Do you know anyone that suffers mental illness and they are in denial that they have it?
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