"When my ex eventually came to take the kids our he took them to visit his parents and she had cut me out of all the pictures, so as not to offend his new partner!"
Linsylou, I get that this may have hurt you, but I think it's understandable. Your XMIL needed to focus on her relationship w/ her DS and his new partner and make sure she didn't offend her. Having pix of his X around her home would not be the way to go. Perhaps it would have been better if she put the pix away, even if it meant not having any pix of your GC around for a while? But she probably didn't want to do that.
Do you have pix around of your X or XMIL for your new DH to see? I bet not. Divorce is bound to bring changes, both big and small, and some unexpected. Removing pix is very likely to be one of them.
I guess I relate to this issue especially b/c when I married my DH, apparently, MIL threw away all the pix of his X that they had in the house. DH was angry b/c he felt it was part of his personal history, and I get that - but I loved her for it! MIL and I had our issues over the years, but I was grateful to her for that one gesture.