My name is Blue!

My daughter got Blue from a shelter as puppy. Blue is one year old, she was great with our other female dog, a Cane Corso, Vesta. However, about 4 months ago, she started fighting with her. I don’t know what trigger her to do that, I think maybe my son was yelling at Vesta bc she wanted to jump on him and Blue saw that and started fighting with her. We still haven’t been able to get them back together in the backyard as Blue is aggressive toward her now.
Blue is very smart, she’s crate trained, has a lot of energy but I think she needs to be the only dog or pet. Not sure how she does with small kids.
She gets anxious when she goes to the vet and around new people so she barks a lot, and my daughter hasn’t had time to get her spayed or get her updated with her vaccines. I don’t want to put her in a shelter because I think she can be trainable if she is the only pet. Blue is going to need a big backyard or area where she can run bc she loves to be out in the yard, she’s pretty active.