Nothing is very clear whether your wife is suffering from Mood disorder / Psychosis or any other type of mental problem but if you feel that her behaviour was not like this before the onset of the present problem, you must take her to your family physician first and if he thinks that actually she needs a psychiatrist's help then only take her to a psychiatrist.

Hi, your wife needs professional help. If she is not ready to go for a check, please consult a female counsellor who will visit your place and befriend your wife. She will take your wife into confidence. Once your wife starts confiding in her, she will feel comfortable and may listen to her to seek help. Every person needs a friend and a friend can persuade her to do things that others can't. If you tell anyone that he/she is mentally ill, the person will react in the same way. No one wants to admit that he /she is in need of a psychiatrist. So please try the indirect approach. Bring a pet in the house, take her for outings and try other things to relieve her from stress. I wish you all the best !!!