How can I best help my wife breastfeed? She has some problems with one breast and loses confidence when she tries to feed with that breast. However I know it's important she uses both breasts to prevent swelling or mastitis.

She should use a pump on the breast that she does not feel comfortable breastfeeding with. I personally prefer my right breast for direct latching and left for pumping. Have not run into any issues as such. Best still I've figured out how to do both at the same time - so I save time!