Respect

Bismihi ta'ala

This is unacceptable. Whatever the family's religion may be, Muslims must honour and respect their families. Your wife has no right to do this. 

If she has certain concerns, you should address them. There might be something she has seen, like abuse, or intimidation, or trying to brainwash your son, etc... Try to pinpoint what the dispute is about, and deal with it. 

But if it is just because she has no respect for your family, this does not give her the right to deprive her son of visiting or being with his grandparents and family. 

With prayers for your success.  

Bismihi ta'ala

This is a difficult question, and maybe even sensitive for some, because we know that Islam unequivocally condemns abuse or physical violence towards other innocent people. 

We must always remember that many parents have not been given the correct method of upbringing, and many parents do not have the adequate skills to deal with parenting and the many pressures that it entails. 

As Muslims, we are taught to always show the utmost level of respect to our parents and our elders. How they reciprocate that and what they do or have done is something else. 

Allah ta'ala will judge them for what they have done. 

We must stay loyal to our parents, pray for them, visit them, be compassionate to them, and never sever ties with them. We must also ask Allah ta'ala to grant us the patience we need to make sure our love for them stays in our heart, even thought they might have hurt us. 

As long as you yourself know that you are not being insolent, or disobeying your parents, or not cutting ties. In regards to your inner feelings, there is nothing much that are able to do, because of the ongoing abuse, but it still does not allow you to disrespect your parents. 

Honour your parents, avoid things that would agravate them, or upset them, in what you do or say, try to get them to understand your position, and how its affecting you, maybe by getting intervention from elders, and most importantly always do dua for them.

With prayers for your success. 

Bismihi ta'ala 

This is an interesting question, and it can be tackled from different angles.

In general, the ruling is that a female (mahram or non-mahram) cannot pray beside or in front of a male. This is not purely a matter of preventing men from unlawful glancing, because if that was the case, then a wife could pray in front of a husband.

Islam focuses on elevating the status of a women beyond her being sexualised by others, and even by herself. This can be seen not only in mandating hijab, but even in the obligatory or recommended (mustahab) acts in prayer, like how she prostrates, and how she stands back up. 

This is all for the purpose of preserving her modesty, and also to eliminate any likelihood of a lustful gaze (haram or halal), during prayer in particular, for the purpose of gaining that absolute concentration in prayer. 

Of course, we are assuming that this is just one of the reasons behind the ruling. It's similar to the story of Prophet Moses (a.s.) and the daughters of Prophet Shu'ayb (a.s.). However, the reality is that like many other rulings, we do not have the precise reason for it. There could certainly be more reasons.We are just assuming that it is a matter of convenience and a spiritual matter for concentration, but it could be more than that. 

The main issue is in prayer we need to attain ḥudhūr al-qalb, which is presence of the heart.We need to be concentrating completely on our prayer, and remove anything that would distract us. 

We understand that it is also the very natural structure of the female that Almighty God has created with her beauty and attraction that could contribute to a male (her mahram or non-mahram) being distracting and glancing at her. 

Please look at all the other rulings for prayer, which can also hint to how important it is to avoid loss of concentration, like praying in front of an image, etc.

It could also be for convenience, so a woman does not feel embarrassed or exposed when she is bending down for ruku' or sujud.

And so on. 

Furthermore, please refer to your Marja' taqleed on this ruling, because there are some jurists who consider it mustahab, and not wajib.

And Allah knows best.