One thing about feelings is that your feelings are not in words. Your feelings function on a mysterious innate logic beyond words, and all we're doing with words is trying to find words to help us make sense of them, and potentially explain them to others.
It's even entirely possible the best we can come up with won't even be right, and warp our perception of our own feelings.
So THAT'S fun.
Is "betrayal" fully encapsulate what Diane is feeling here? Probably not, but it's the best she could think of.
It's kind of like when you want a very specific scenario for a TV show, and you find one that's really close, except for some reason there's a talking wombat, and you don't know why there's a talking wombat, but you watch the show anyway, because it's as close to what you want as you can get at the time, even if it's not exactly what you want?
Words are hard.
Seriously, though, what's with the wombat I just made up for that hypothetical show?
Why are they there? WHY CAN THEY TALK???