Ok - I just cannot agree with last two posts (before yours, Swargolet)...
She doesn't want you anymore...she wants to move on. It might seem "selfish" but come on, do you really think that she should just pres pause because you're having a hard time getting over her? I know it sounds harsh, but she didn't do anything wrong here.
It's a sad fact, that you have to live there with her, of course. But still - it's you that cause the most damage to yourself. You're listening to their phone conversations > why the hell would you do something as crazy as that? "For some reason you're unable.." you say. Oh, please. Open your eyes mate. Do what people advised you. No one said that you should avoid her at all costs - just limit it to the minimum. And let's be frank, you're not.
As for being friends after a relationship - are you guys serious? Do you really believe a sensitive person that just got hurt is able to turn the page and just be a friend to someone that just broke up with him? I'd say thats just a desperate attempt to stay close with an excuse (= being friends). You can be friends and you probably will be too...in time, not now.
Here's a simple test: are you happy for her, seeing this other guy and having fun with him? A true friend would be...
I still think you're not trying hard enough. You're falling appart there - do your BEST to get her of your mind. Try talking to her father and her together about that, I'm sure they'll somehow understand. Don't have lunch or dinner together, don't do anything together. And don't say you can't because you live there - it's doable, trust me...just do it goddamn it!