@Alex S
You've gotten accurate information to date. She definitely sounds broody. Not all broody hens are vicious divas. I have several who simply sit quietly on the nest, puffing up if you come near, but not striking out. (I have others who will try to take fingers off...just depends on the hen).
If you don't have roosters, and don't want more, then yes, breaking her is probably the way to go...UNLESS you ever want to use her as a broody hen. I do not recommend breaking them if you plan to ever use them as a broody in the future. It encourages bad habits.
To break, you can simply remove her from the nest several times a day placing her far from the nest. Better yet, block her from the nest. This will discourage a number of hens except for the dedicated.
Those who are dedicated and do not break with simple intervention generally need a "broody buster cage." The idea is to put them in a wire cage (with wire close enough so that they can't step through it). You place nothing but food and water in the cage as you want air flow to literally cool off their underbelly. You may consider lighting the cage area to also interrupt the brooding cycle. (Broody hens are propelled by hormones that are supported by heat, darkness, and pressure on the breast bone). Interrupt any of that heat, darkness, and pressure of eggs can break the cycle. It often takes a couple of days in the cage to do its job.
With the very, very dedicated, they will simply go back to brooding again. Just make sure they keep hydrated and fed (they will generally do that themselves, once a day, but watch out if they really languish on the nest for more than 4 weeks).
With those very, very dedicated...I give in and give them eggs to hatch as that is the only way to break them...or find chicks.
Otherwise, it is physical support until they simply give up.
But hopefully simply removing her from the nest and barring her from going back will discourage her enough. Feed her nummy treats out in the yard to reinforce yard "happiness."
Good luck.
LofMc