“Today she said she was going target and the kids said they wanted to go to target instead of mass. So they didn’t go! I am done going to her church and will only be going to mass.”
Can you talk to your wife about gaming this out beforehand, so that you will have a pat, thought-out answer to them? She shouldn’t be leaving you open to attack from the kids like this, and particularly not to go shopping. How would she like it if when she wanted to take the family to her church, you said you wanted to go fishing, and lured the kids off with you? You guys need to remember you are on the same side and you need to not let your partner down.
If you are expecting the kids to go to both churches every Sunday (which is a pretty big thing to ask), perhaps you should spread it out between Saturday and Sunday?
Another related issue is whether or not your wife should have been going to Target at all on a Sunday. If it was milk or diapers or medicine or something vital, I understand, but there are 7 days in the week to buy everything else.