Oh man, I am going through the EXACT same thing with my husbands family. He has not had a relationship with his mother or family at all and does not want to, won't call them, won't visit. Once we had kids suddenly his mom wants in his life and he just outright refuses. Well, I tried to pull everyone together because I am a big family person and it backfired so bad. I started talking to his mom, which then turned into her asking me to have him contact her and so on, then when he never did and he told me to butt out she attacked me on a public forum as well saying that it was all my fault that he was not having any relationship with her and that I was controlling him. I also told her that he was an adult who made his own choice and that I did try to have us all be close but she says I lie.
I have just learned to walk away from it. If hubby does not want relations with his family, then leave it be and don't contact them again. It's not worth it. Just focus on your family and relationship and if someday he wants to have a relationship with them then support him. Although I will admit, after the way I was treated I would be just fine with my hubby not persuing a relationship with his mother in the future. My kids don't know them nor care to.