Friend's Girlfriend is evil?

Ok maybe she's not the anti-christ, but she's pretty close. Here's the crap she does to ME. I'll call him on a Fri/Sat. she'll answer HIS phone and say WHAT DID I TELL YOU ABOUT CALLING JAMES ON THE WEEKEND?! in a very angry voice. First of all, he pays for his phone, not her. I have just as much right to hang out with him as she does. He has no plans on ending this relationship, and will propose soon. I think it's a mistake. I know she doesn't like me because I'm his only friend she treats like this. If he left his phone out and she answered cuz he was in the bathroom, I'd be fine with that. It's not her decision to say "give me the phone." and then answer it. she pulls crap like this all the time. I once was having a good time hanging out w/ the 2 of them and I asked her why girls go to the bathrooms in groups. she said "SO we don't get d dumb-as$!" and I personally don't think that's a dumb-as$ question. I really didn't know. I don't care if she's on her period or whatever, that's no excuse to treat me like that. He won't stand up to her, but I have his permission to do it. Think I should? and how far should I go? I know she'll use profanity, but I won't cross that line.