While I understand you're hurting, I'm actually more concerned for the other guy. He's being told she loves him and he's the only one, when in fact he's perceived by her as the secondary. That's pretty damn far from being "the only one."
My other concern is about her sense of honesty. She's lying to this guy, is she also lying to you? Could her desire not to talk be connected to a tendency to avoid telling you thinks you should be aware of?
“As I am sure any cat owner will be able to tell you,
someone else putting you in a box is entirely different
from getting into a box yourself.” —bisexualbaker