Maika, this is something I actually have experience with. Parents will always stick with their own children and it is rightfully so. You will not be able to make your in-laws see your side, even if deep down they know their D left your MR, they will find reasons to justify her decision. In my case my MIL was living with us during and soon after D, she saw me at my worst, staying up whole night, not eating, contemplating suicide even with 2 small children and I definitely did not handle the BD well. But once WAH spoke to her, she sided with him in spite of knowing the hell I was going thru and her small grand children are having their home torn apart. There is no winning with in laws, they are related to you through her, I wouldnt worry about what they think of you. If they are great and mature human beings they will see the truth for what it is, the remaining 99% will support their children.