Compassion and Love
Oh Sweety, I feel your pain. I really do.
Ok, here is the short of my story: I started out in a mono marriage and then my husband decided that he was poly. He gave me a terrible ultimatum (either accept his poly or get out). I stayed because I loved him, I knew anything could be done, if I just worked on myself. so I tried and I tried. eventually, like you, I met a nice man at a festival and we hit it off. I started dating him and my husband got terribly jealous. Instead of working with me on his jealousy (like I did earlier that year), he just closed off to me and stopped sleeping with me. I broke it off with my bf because I only ever wanted my husband to be happy. Not even 6 months later, my husband happily went into another relationship....that's when I realized he wasn't treating me as an equal.
I sought counselling for learning how to value myself more. (BTW, I reccomend "The Undervalued Self" by Elaine Aron)
Now, I'm not here to tell you the end of my story or what happened to me, but I think some of the elements are the same here.
Firstly, jealousy is hard to deal with. It's takes a lot of courage and humility to deal with jealousy. I can see your allure with regards to your girlfriend: with you she never had to deal with jealousy. You were like her adoring admirer and she never had to share you.
The thing is, she is not seeing all the work you have done, facing your own jealousy and your issues.
I am going to tell you something my therapist told me that was really profound and it changed my life forever: Relationships are not about who is right and who is wrong. They are about if people feel loved and cared for.
That's it. there is no wrong or right. She can throw every professional saying in the book at you, but if you don't feel loved, cherished, or treated as an equal, her argument is worth nothing.
This is not a quarterly financial statement you are arguing over, it is YOUR HEART, YOUR SANITY, YOUR WELL-BEING.
I wish I could give you a hge hug right now. I know, because I really needed them. Go to people who make you feel loved right now.
Another piece of advice, it is a sad fact, but people who are just becomeing poly, or who are mostly mono, are not very respected in poly communities. I know from previous experience, that you are treated much differently - given more clout - if you have been actively poly for a while and it can lead to some people in the community being "poly tyrants".
The thing is, you don't stop learning, once you have been poly for 5 10 15 years...there is no magical moment that jealousy dissappears and all of a sudden you are an invincible poly superhero. Every poly person must work on every relationship. It is our duty as being rational adults, and humane people.
What your girlfriend is doing to you, is not loving, it's not compassionate, and it's not helping.
I wish you the best of luck and that you will be able to do what is right for YOU.