Legal Question in Family Law in Nevada

8 years is a long marriage. At 8 years, alimony is a consideration. When you married her you likely promised to care for each other "in sickness and in health" and, well, she is sick. If you have the financial means to help her, the court will prefer you do so rather than forcing the rest of society to do so (depending on the judge, the alimony could be more or less so it is important to hire an attorney).

With regard to annulment, the length of your marriage suggests you should have known of her mental illness long ago, such as within the first year of marriage. If this is so, than you have long since ratified a marriage that could have been voided.

My only additions to Mr. Wright's comments are that "incurable insanity" remains on the books as a grounds for divorce (but pretty much automatically triggers a duty of support, and so is essentially never cited for grounds), and pretty much any cause of action for divorce could be used as a ground for annulment; notably, in an annulment, IF you could succeed in proving it up, property would be divided, but no alimony should be awarded. Mr. Wright is extremely correct in recommending at least a full consultation with competent counsel before you make any decisions.