What if it were a "legit" medical problem that affected her moods and made her unable to have sex..would you be looking around then? It's not her fault her hormones are all futzed up, and frankly, a good chunk of the options (like hormone replacement therapy) have side effects (like breast cancer) that make the symptoms preferable to the treatment..she may feel more like she doesn't have any viable options, than actually having no desire to 'fix' it.
"Well, now she says it's not menopause, but all my son's fault. You can blame me for everything but leave my son outta this. He's with us two week-ends a month. "
Have you tried to help her find assistance, be it medical or more homeopathic? If you approach her with the mindset that you're in it together, rather than it being her problem that you're forced to 'deal with', she might be more open to letting you help her. Friendly warning: if you come at her with the attitude that you are sick of dealing with her problem, you're shooting yourself in the foot & you may as well just move along now. Speaking as an older, very hormonal (but not menopausal yet) broad, we don't enjoy this hormonal hijack of our bodies and minds any more than you do, so treating it as if it's her fault isn't going to help, but approaching her with more of the tone of wanting to get through it as a couple will meet with a much more favorable response.