First, we need to clarify some language. You don't receive a summons for a wage garnishment. Look at the bottom of the form. It will have a form number. Then you can go to www.courtinfo.ca.gov/forms and search by form number. That will tell you what the form is.
If it is a summons, it means your wife has been sued. You need to file a responsive pleading. There are a variety of choices. You can read more about responsive pleading options at my blog www.californiadebtblog.com. If it is a wage garnishment, it means you have already been sued and there is a judgment against you. You may be able to file a claim of exemption.
You should talk to an attorney about your options. There are a variety of options, but they are too numerous to list here without knowing exactly where you are in the process.
My best advise to you is to seek the advise of a competent bankruptcy lawyer. Most bankruptcy lawyers offer a first visit free consultation. Make sure that you select an attorney that has been practicing law for a considerable period of time and who's emphasis is on bankruptcy law. When you call to make an appointment be sure to find out what documents you should bring to your meeting in order to get the maximum benefit from your free consultation.
A bankruptcy proceeding will stop the garnishment. In a chapter 13 you will be able to repay the debt in an amount you can afford and without a garnishment.
Although I am in Maryland I can say that unless you agreed to be responsible on some credit card application that you should not be liable for your wifes debt obligations even though it is a community property state as that term applies primarily to domestic issues