Tried to put it better, but what I say below is rather blunt - please don't take it as having a go, just trying to say as best I can how this seems to me, with the words you have given....
You haven't told what sort of handling she's had. Eg. What does 'ground broke' mean? Was she just forced to put up with things when she was younger or some such? I'm presuming nothing has been done with the filly in some time - how long? What about healthcare? How have her hooves been dealt with? Worming, teeth, etc?
It sounds like you've just taken her out of a paddock where she's been left to be a horse & not bothered to teach her that being with people can be a Good Thing. Now you want to just do things to her that are unpleasant & scary, without considering how she feels & how you could *teach* her that things are OK & even Fun & Nice.
I'd personally forget about saddles, bridles, especially riders, until you've got a good relationship & understanding with the horse first.