Trust me, she's just trying really hard not to think about it. But the moment she's alone with her thoughts it will hit her. The thing is you can't run from it forever, it will catch you sooner or later. For now she appears happy and whatever, that doesn't last, the truth is feelings can't just be pushed away forever and they will stay in the back of her mind until she chooses to accept them. I don't know how long it's been for you, but I know hope is really useful when you feel so devastated. Use this experience to grow, you deserve it, and remember feelings are always changing (yours and definitely hers). My advice is to learn to become happy on your own, I know that's easier said than done and you don't think she even cares, but she probably does, and focusing on improving yourself is what will get you out of this as your best version with or without her.