I thought she may be intact.
When was her last heat? has she just come in or coming into heat? Sometimes if females are at the end or the beginning of their heat cycle a male dog coming around may just set her off.
It almost sounds like she was protecting you all. If the male just rushed in from out of now where?
This dog should have been spayed. Why is she still intact?
The whole set up of where you live is setting things up for failure. A dog with a doggie door that is allowed to go wandering around all over the countryside?
That's just crazy in this day and age. Labs tend to wander too...they don't like staying home.
When two dogs are fighting and you have enough people around...each person can grab a dog by the back legs....and start pulling...wheelbarrow style. Also I've used a chair and a steel garbage can lid to wedge in between two dogs.
I would honestly move....have the dog spayed and get into some training.
Gina