The way a family stops bickering is when the family all works on doing simran together and when the 5 (lust, anger, greed, attachment, pride) stop controlling us and we learn to stop our thoughts we can work in harmony. Family is supposed to be our sangat. Unfortunately lots of families these 5 have taken over and people are unable to get along. We cannot force other people to change or to work on themselves, but we can work on our own selves and limit our interactions with people who bring us down. Your wife was right that you should not bother to be angry and waste your energy arguing and fighting. At the same time, you don’t need to do what they want, you don't need to take the advice. Are they living with you? If they aren't then its simple, you raise the kids how you want. If they are part of the caregiving though then it makes it trickier and you kind of have to work together to some extent.
You are doing your best. You don’t need people in your life who are bringing you down right now, its hard enough when you just lost your wife. Just try to understand that perhaps they are feeling their own grief and that they have their own point of view, and leave it as that. Don’t try to argue with them, you don’t need to listen, you just do the best in taking care of your kids.
I think it is excellent that you are going to the Gurdwara, and your family is wrong to discourage that. They can live however they want but you don’t need to follow them. There are lots of positive things about brining your kids to the Gurdwara- like learning about Sikhism, support, maybe friendship with other kids or positive female role models (which may be especially important for them right now), etc. Importantly for you right now it may be hard to plan meals and you get to have some of your meals be langar instead of at other people’s houses or take-out meals, etc. It doesn’t need to be a last resort, this is what the Gurdwara is for and this is the purpose of sangat. Do you feel trapped when you are there because your family is telling you not to go?
