Hi Kmk2009,
I agree with the other post that your wife is lucky to have a husband who is so concerned. Physicals should be done once a year and they usually run complete bloodwork where they could check her hormone levels to see if she peri-menopausal or in menpoause. If she still has her monthly cycle then she could be peri-menopausal and it would show on the bloodtests. For PMS and peri -menopause she could take the supplements evening primrose oil and estrosense or menosense if she's menopausal. These are available in Canada.
Make sure when you're talking to her that she knows you trying to help as opposed to just making the statement 'you need help'. I'm sure you're not doing that. There are also good books on menopause. I wish I could remember her name, but she the female specialist on Oprah. Maybe you can get her interested in going for some long walks where you can bring up the subject. I think you also should try to be a little firm with her, to get her to take some resposibilitiy for her own health and get her to be pro-active. She has to understand that you and the kids shouldn't have to be victim to her moods. Maybe you can go and buy some books for her. Best of luck to you and your family.