My wife shattered her back and I mean blew apart t5, fractured all the spinous processes down her back, so she does know chronic pain. Which is helpful. We have come to a bit of an equilibrium, i'll ask for say essential oils on my temple area or she will ask if I want them, it does next to nothing except maybe the scent is slightly calming, but she feels like she helped and I let her. We both know the truth but it gives her some control or input into "helping" she also did a crapload of research and funny thinking now, Lamaze breathing can help during an attack, something she found. She will also get my o2 ready, grab me a pill or ask, I just have to nod or shake my head, gives her a sense of helping, feeling not so helpless. That is one thing she has conveyed to me, how horrible it is to feel helpless to do anything, some of her fear and frustration stems from that.
You have to accept she will never truly understand, she will have to simply believe you.
Edit I have found meditation, guided, helps in between to stave off those "omg what is the next going to be" Headspace, on any device is a great app.