Cafegal, I sympathise completely with your position, you are obviously trying very hard to work on this relationship and given how hurt you are that’s admirable.
You say your kids don’t like to talk on the phone, maybe instead of calling try texting more regularly?
I understand your main focus is on getting to visit, however I would suggest you don’t mention that for a while and work on texting and getting into conversations that way? Also with DIL, it must feel natural when communicating to ask how are you and the kids, but again I’d suggest solely focusing on her.
I understand your frustration, I really do, but what you’ve tried this far hasn’t worked so maybe changing your method of communication to the way they’re more comfortable might yield you better results.
In the past I felt that when my IL’s text/called the “how are you” niceties were for show, not a genuine interest in me as a person and as a way to access my children. Even if you are genuinely interested, by focusing solely on your relationship with DIL and trying to strengthen it you may be able to build a trust that has obviously been eroded somewhere along the way.