Hi S&G,
I'd like to second what Mum said and that is, your wife has to go at her own pace. Let her know your expectations for your relationship, what you can accept and what you can't. Brainstorm solutions to managing specific trouble spots. I know I squirmed and whined trying to find a path of least resistance and maintain the status quo...fortunately, my psycho SIL really pulled a fancy one that sent my Ndad over the edge and they proceeded to duke it out. As a result, we no longer have holidays together. Merry Christmas!

Love that. My H is estatic.
To answer your question:
Miss Piggy, a thing that I am thinking of right now from your post... I have been backing
off significantly from the relations with our N's. Part of it because they have been
pushing me away ('I'm sick of speaking to you on the phone', 'Stop saying 'We'',
'You should not be the one to do (or say) this, she should', etc...), part of it because
I am thinking that they are my wife's parents and she should be the one dealing with them.
Geesh, do they really say these things to you? Toxic!! You know, I thought about the phrase that is often overlooked in marriage ceremonies. Something about a union and let no one put it asunder. That is, you and your wife are a "package deal". Just a thought.
Do you think it is OK or should I are rather be more 'protective' or more 'together'? It seems
to be working (note that I love the image of taming our N's like wild animals).
Well, I don't really know enough about the situation. I can tell you that in the case of my H and I, it was really helpful that he backed me up as it was my family that is so difficult (because they are closer geographically). We would have similar issues with his, but they live farther away. Now that I think of it, I have read in more than one book on the subject of Ns etc that the best way to deal with truly destructive Ns IS to move away. And they know it. In a way, their brains only know what is right in front of them and you would become out of sight, out of mind. No supply. But your wife needs to buy in on this. Otherwise it will become an issue between you instead of working for you both. It sounds like she has a ways to go.
But she really does need to speak up for herself, even if only to back you up in principle. They need to hear whatever you both are putting out from her. We had a nasty showdown with my Ndad (actually two really notable ones). Real firebreathers. The first one my H did the talking and I told my dad "it's important to H, so it's important to me". That is, we stand together. The second one I did the talking and my dad blasted me and my H followed up. "it's important to MP, it's important to me, we would hope you would care about it too." This last matter was about not being required to stay overnight at their house and sleep on a cheap sofa bed because I was nine months pregnant. Yep. Big inconvenience for HIM that I didn't do this. ??? That's the level of BS we deal with to give you an idea. And H would return the favor when his dad pulled some inappropriate stuff, like handing me his dirty underwear when we all shared a vacation home. Uh, no. I'm not your mother. H had to gently scold him like a toddler. For some reason, this works for them.
Really, I guess my answer is, there is strength and safety in numbers. Don't let them divide and conquer. As for the job opportunity, make sure you are moving towards something you want, not away from something you don't want.
You know, communication is the most important thing for a healthy, workable relationship and it sounds like you and your wife have it. Note I didn't say "constant agreement". Take it one step at a time, that is, decide on a game plan to deal with mr and mrs Toxic, execute the play, do a very short post game analysis, then play with your kids.

Hugs, MP