Complex, you are young and haven't known your W's family that long. Georgia is probably right, you won't have a long relationship with your W's family.
But you never know. Every family is different.
I told my MIL and SIL of my W's A, but months after it started and when I was in a particularly stressful situation. They already knew something was up because W had stopped talking to them - she had restricted her friend base down to those who would support her. I have their support - both my SIL's still contact me, they know W is messed up, they don't believe 80% of what W tells them, and they hope I'll still be around when the crash comes, but they'll understand if I'm not. But I also know not to put them in a bind; as much as they do not like W's actions, they are family. And they are aware that we are all powerless over W's actions.
I guess one way to put it is that we are all pulling for my W to get herself together and start making better decisions - we're all on that same team, so nobody feels they have to "take sides". That comes from knowing them for nearly 20 years.
I'll say this. Don't worry about your in-laws. Your W is going to paint the picture the way she wants to, and your in-laws are going to see what they want to. You can't control any of it. Guiding principle - speak only nicely of your W. Fake it until it comes naturally, and it will.
Meanwhile, work on you, without worrying about what family, friends or the rest of town will think about any of it. Frankly, none of them probably care nearly as much as you think they might.
