We've talked about her ignoring calls, but actually answering the phone then leaving the room is one step up from that. Again, there could be a legitimate reason for it, like she's secretly buying you that 30ft yacht you always wanted. But if there's no reason for it, then it looks like this is definitely the end of the road.
You should read this kind of behavior as essentially saying that she doesn't care about you anymore. She no longer has the decency to take her infidelity and keep it outside of the house, and she couldn't give a flying penguin whether you know about it or not. Why would she be so brazen? Well, that's a strategy in itself - to make you do all the dirty work and break up with her. So you're the bad guy.