If she keeps interrupting you, it might not just to annoy you. Maybe she wants your attention. Maybe you two used to be closer before you and your girlfriend got together and she feels abandoned by you, like you chose your girlfriend over your friend. Especially if you knew her longer, this would hurt and may explain why she's mad and, since none of us are perfect, she may express her feelings in ways that hurt you. But honestly you know we've all said things to hurt others, even if we don't mean to and regret it after or out of anger at the time, so forgive her as you'd hope she'd forgive you. And this applies not just to her, but anyone who hurts you. You're not perfect. None of us are, so forgive others and try to understand them. You may have a lot more in common than you first realize.

urm um what they said. ^

I don´t get this... You are two persons and she´s alone, right? Why don´t you just shout at her? I don´t want you to become violent, of course not, but if she keeps annoying you and doesn´t listen to you when you want to talk to her, scream you opinion into her face! Maybe she will let you alone then. And if you and your girlfriend are rather calm persons there is no other solution than ignoring her. She will get bored after a certain time.