thanks for the replies guys. i torched her car and spraypainted angry messages all over her house, so it's all good now.
but really, after I slept on it, I woke up feeling a lot better (or perhaps it was after reading your replies that this happened). I don't really feel that initial jealous feeling. She is extremely open to communication, as am I, so talking about all of this is definitely possible...
but I haven't really been able to make myself bring up the topic of polyamory. I might have to save it for next time I see her in person (we spend time together about once a week usually).
How can I talk to her about polyamory? What am I trying to gain exactly is my question. We've established what our relationship is labeled ("friends with benefits due to time constraints and nonexclusivity" (to her, dating is spending lots of time together, and being exclusive), but would changing that label to some sort of poly relationship really accomplish anything?
I'm going to have a better look around the forum but I would still appreciate any specific advice too