Damn, this sounds familliar, only the other way 'round.
When I was a teenager, I fell in love for the first time. My parents hated him for a while, then Mom accepted him but Dad wouldn’t. I finally broke up with him and naturally, he was quite welcome to drop by anytime after that. We stayed friends until he died in '91 and he often went to see Mom and Dad for coffee or to help with the lawn etc.
When I was twenty, about five months after I broke up with my first bf, I met Mr zoogirl. Once again, my parents hated him. This time I stood up and moved out of the house to be with Mr zoogirl. What a nightmare! I was totally freaked out. I cried at the drop of a hat for months. Looking back, I was just plain scared out of my wits about being out on my own, even with Mr z.
I can see a lot of myself in your girlfriend. My parents continued to refuse to allow Mr zoogirl on their property until our second son was born. By then Dad was gone and Mom was too sick and in need of our help to object. She’s gone now too.
We went through a pattern of breaking up and getting back together for years. I think we probably should have stayed apart for a lot of those years. It’s good now, mostly I think because we’ve matured. It’s been twenty + years and a long hard haul. In your case, without kids and with a chance for a clean break, I’d say let it lie.
I guess what I’m trying to say is, are you prepared to wait it out until a) her parents die, or b) you’re both in your forties? If not, stay out of it.
I’m a big advocate of counselling. Get it, stick with it and learn all you can from it. As you obviously know, writing can be a big help. Keep a journal. It will let you see your progress and you can rant into it all you want. Get busy too, If you don’t have gas money, take a walk. Pick up a cheap secondhand bike the next time you DO have money and you can at least get out of the house and away from the phone. Ride until your exhausted and hungry and make sure you take a lunch with you so you can eat right away.
Good luck!