A person who is an alcoholic may have had a parent who was an alcoholic. A person with gambling or drug abuse issues may have had a parent also likely afflicted; the genetic markers that cause these predispositions are already imbedded in that person’s DNA. And then there are those people like your wife, who seemingly, six years ago, suddenly had a personality overhaul that caused this manifestation.
Did something happen back then that may have caused her to look for fleeting satisfaction in endless shopping sprees? Did something upset her so much that she needed a way to “feel good” and found it in spending money on things she doesn’t really need and will probably never use? Does she have low self-esteem or perhaps feel unloved and useless and therefore uses shopping as a reason to feel worthy and useful to her family? Is there anything you can think of that may have triggered her compulsive need to shop in order to feel fulfilled and momentarily happy?
She is obviously aware she has a problem by virtue of the fact that she excuses the clutter and mess whenever a repairman makes a call. If she was not cognizant of her problem, she would not have offered an explanation and she would have no feelings of embarrassment. This is a hopeful sign that once her emotional issues are addressed, she will no longer have the need for artificial stimuli.
If she will not consider counseling, you could try to change your approach and, in a kinder, gentler and more loving way, show her what this is doing to the children. Explain that you will help her dig through all the stuff and she can keep what is important to her and then give the rest away to tzedakah organizations. In this way, she will feel she is helping others while she helps herself overcome her insecurities with the help and support of her loving family.
I’m flying a bit blind here, but it’s worth a try and it has worked for a few people with similar issues. Remember, everything has a source from whence it begins, so try to figure out what has caused her so much hurt that she had to develop an alternate means that gives meaning to her existence. I wish you the very best of luck.