It is difficult not to get bitter, yogagran, but I have come to the conclusion that my DIL's behaviour comes from insecurity and resentment at the relationship I had with my son long before she was on the scene, so now I ignore any bad behaviour on her behalf and carry on with the relationship I have with my DS and GSs. I hope in time my DS will see her behaviour for what it really is, but in the meantime there is no way I can change it so can only change the way I react to it. It seems to be working in that the relationship with my DIL is now much easier because I refuse to get drawn in.
My GSs always say thank you for the presents I send, either by phone or by SKYPE but I don't get any genuine feedback so don't feel that I really know the GSs at all. Having said that, I got the briefest of emails from my DIL after Christmas to let me know that one of the presents I sent them was an absolute smash. So, maybe progress is being made slowly but surely, but you have got to be in it for the long haul ;)
A good suggestion, jingl, and I have tried that, but any cards or postcards etc which I have sent fester in their mail box until I chase my DS up to go and look for them and then pass them on. So, back to my earlier rant about men..
My mantra has got to be STAY CALM