I always end up with an uneven number of arms on either side of the hug. Just so you know. <3
I hang around on "straight people" boards, too, not just polyamory.com.
They judge cheaters and the people who help them cheat pretty harshly, but a few of us are non-monogamous by nature, so we've been teaching them the difference between ethical non-monogamy and cheating. Mostly it has to do with the "ethical" part, which I'm guessing your friend isn't understanding too well right now.
What's important is that you aren't letting her dictate your values. I'm proud of you for that. I've been there; I've lost friends who thought I was hell-bound in some way or another. Those same people accused me of some nasty things in a very public place. (Those same people, ironically, spent high school getting drunk all the time, but God loves a boozer better than a queer!)
If it helps, we're here next time you have a lonely night. Stay strong and don't forget that your username means "beautiful", 'kay?