I was very very disappointed to find that no one in my H's family CARED enough about me to ask me how I'm doing or acknowledge that I'm in a hard situation. If you ask them they'll say they care. But what they cared about more at Christmas was to avoid any unpleasantness my emotions might cause.
Adinva,
Just like getting upset about your SIL not calling you, I think you need to be more explicit with these people about what you want and need. If they don't deliver then, go ahead and get angry. It feels to me like you are looking for some mindreading on their parts. They probably care for you more than you are giving them credit for but don't know how to handle this situation. It's awkward and difficult and hard to know what's appropriate.
When my sister left my BIL, I had no idea what to say to him. I thought that anything comforting I might say would sound hollow and/or falsely reassuring. I thought that my attempt to empathize with him would make him angry because there is no way that I could know what he is going through. I was also afraid I would put my foot in my mouth in some way because I didn't and couldn't know the whole story.
Therefore I did a crappy job letting him know I cared -- but I did. I just had no idea how to approach the situation and feared making it worse Had he told me what he needed or what I could do I would have been all over it.
This situation is completely foreign to your inlaws. I think you need to make the first move and be explicit if you want some compassion and/or support. It will feel crappy to have to make that first move, but if they respond the way you want, that pain will be quickly forgotten. If they don't step up then you can leave them behind without regret and know it wasn't just a misunderstanding. Tell them what you want and see what happens. Make the first move. They may surprise you.
Accuray
Married 18, Together 20, Now Divorced M: 48, W: 50, D: 18, S: 16, D: 12 Bomb Dropped (EA, D): 7/13/11 Start Reconcile: 8/15/11 Bomb Dropped (EA, D): 5/1/2014 (Divorced) In a New Relationship: 3/2015