It is not wrong to want to care for someone with dementia, but you need to understand what you are taking on.It is 24/7, and the situation gets progressively worse. cared for my partner for 7 years, he had dementia , and at the end I had a stroke.I always thought I could beat his disease, although I knew in reality I wouldn't,but it was called hope
Just make sure that you have all the support available to you , sitters , respite and so on including day centres, social workers, GP and so on.
Never be hesitant to ask for or receive help.
All the best to you , if I can help further with any thing , you know where I am , don't hesitate to leave a message Brenda