No, I don't think it's "disloyal and disrespectful" for you to keep up a relationship w/ XDIL, potter. I agree w/ posters who say it's important for you to do that b/c of your GC. If she's ignoring you, I don't see how you can explain that to her though. Perhaps DS can relay it to her, but IDK.
I'm wondering who she thinks you're being "disloyal" to. Her? DS? And why suddenly get upset last October? Like a few other posters, I wonder if something happened around October that set set the partner off. Do you know/Can you think of anything?
Or maybe she was asking you and DH to stop being friendly w/ XDIL for a while, but you didn't (understandably), so she decided to go NC? As a poster mentioned, this would fit in w/ the kind of advice being given these days ("If the issue continues, just go NC.")
Regardless, as long as she's not trying to make DS go NC w/ you, I don't think you need to worry. It hurts to be snubbed, I know, but as long as you and DH can maintain a good relationship w/ DS, I'm sure you'll be ok. Granted, it may be embarrassing if you address her in front of other famiy and she doesn't reply. But the remedy for that is to avoid addressing her. I agree w/ you and DH to just focus on your relationship w/ DS - and, of course, your GC.