Protective

I have a female JRT 4 years old, named Xena; (we adopted her from the Humaine Society of Broward County); she does not like any other animal especially other dogs (Various Breeds) around her and she makes it clear to all. I have asked my neighbors politely to keep their dogs in while I let her out. Some times she is on a chain alone out front -No Fence- and other times my son and I walk with her. There have been quite a few times where they have not taken my advice and their dogs come around to my area and Xena gets very aggressive; one instance a Chihuaha was barking at her and approached her and they fought and of course Xena bit the other dog.
I am a little worried about her tasting blood. Is it a big deal. I know JRT are meant for hunting and some people have told me once they taste blood the become VERY aggressive.
Am I crazy for being worried? I didn't yell at her because I don't believe XENA did anything wrong. And I will now be walking with her all the time.
I would really like your input on this. I will be waiting.
THANK YOU!!!!!!!