I don't know how long a relationship you two have, or how long at this place, with those roses.
First let me tell you, they will probably live.
I know, that is NOT the point though.
My dh and I have an agreement about the yard though - he stays on HIS side of the land scape timbers, and I stay on MINE.
If he weed whips off the top of my flowers, he knows I'm gonna tell him WHAT. And I don't mess up the grass. It's about respect, not the lawn.
I don't think you're being too sensitive. I think those were YOURS and if they were in somebody's way, somebody should have asked what to do about it, and not just hacked them to bits. Somebody owes you an explanation and an appology.
If her car was in your way, would it be okay if you just rammed it with yours? I don't think she'd think so!