She replied: I told you I didn't want to hear from you! I just wanted some answers. But I guess I won't get any! Sorry I bothered you. Later just tell me what personal boundaries are?
So she, predictably, shifted into the role of victim, keeping you the persecutor.
No response is needed for her last message to you. You said no... stand by that.
Even if you do end up going no contact, understanding the drama triangle will help you process what happens with you, your mom and g-ma. Being raised in the sort or environment we were, we are all at risk of getting involved in dysfunctional triangles... I specify dysfunctional because some triangles are healthy and stabilizing. Learning to differentiate between the good and bad is important.
I think I need to commit to full NC. There is no convincing them to hear me out and all I get is deflection and denial over and over again.
We can support you as you make your choice. Regardless, having appropriate expectations is also important.