I need someone's advice about sending postcards

Hi,I am a birthmom and i have a heart-wrenching story to tell. My husband's mom supposed to help out to take care of our twin girls. We sent her money and called, she seemed o'key with everything. Since we livein different states it's not easy to visit. The initial agreement (verbal) was to help us for two years. Half year before that my mother-in-law states she wants to adopt our kids. We hired a lawyer, we knew nothing about conspiracy she had for year and a half. She made 3 other relatives to lie in court. They made me cry in public. She adopted them easily because of that. Now she sent us postcard saying she is giving our kids to her daughter to raise them. NOW, I HAVE A QUESTION Since i know where my kids going to live now (they are 3 y.o), can i send them Christmas card and Birthday card every year for them to know i love them. There is no court order for me not to communicate with them, i committed no crimes. Can you please give me advice on that?Hurt, but hoping.