Mild antianxiety medication may help some. But the best way to help your wife is to have someone like a nurse or home health care relief her 2 to 3 times a week. It would allow your wife to have some time for her.
You need some relief. If your mother has health insurance you may ask about home health care or a visiting nurse to help you. Medicare usually covers some of the services. You have to request it.
I had severe postpartum depression after giving birth to my son. Is it likely I will have it with my second child?
1 on 1 therapy may be very beneficial. Therapy and meds work better than either one alone. There are self treatment materials available (books, exercises, etc. Google it. Very helpful stuff). The best treatment I believe is recently approved by FDA d.TMS (Deep Transcranial Magnetic Stimulation). Look it up at www.brainsway.com