You have a great responsibility on your shoulders, in not only honouring your revert wife in the best way you can, but also showing the highest standards of Islamic Akhlaq to your in-laws. You represent Islam, and they see Islam through you. Even though they might be atheists, or followers of a religion, for you it is of utmost importance to conduct yourself in the best way possible.
Your wife also has an important duty in trying to maintain the relationship between the two families as civil as possible. Along with her studying about religion and deepening her understanding of Islam, she can also engage in polite and productive discussions with them.
When she does this, there will be no concern from your side that she is being negatively influenced. If she is strong enough in her faith, then even if a discussion becomes heated, it will not effect her.
Yes, it might be frustrating from your side, and all you want to do is just socialise with your in-laws, but they bring up topics that might aggravate you.
The extent of the relationship is that you honour them, as your in-laws, and that you avoid arguments or anything that would tension things between you and them.
You should maintain patience, and think of the bigger responsibility you have. Always do dua for them, and pray for their hidayah.
With prayers for your success.