My aunt on my moms side had a child(girl) with my dads brother (my uncle). There's speculation that my dad is the father.......?

they would need to do a dna test to show who the father is

stop watching TV/films

Genetically, it's extremely hard to tell a half-sibling from a cousin.

Full brothers and sisters have on average 75% matching DNA on the given DNA markers presently used in identification. A full identical twin will be a 100% match while it's impossible for it to dip to below a 50% match, and an only 50% match is about as rare as an identical twin. That means your dad and his brother are probably around a 75% match for each other, but the range can vary. They could be 93% matches. They could be 62% matches. With what you're suggesting, the lab testing the DNA would have no idea where in that wide range they fall as matches, which makes figuring out how much DNA you and she should share for each of the two outcomes to be probably true impossible as there is overlap in how much a half-sibling and a cousin possibly match each other.

So, without either of their DNA, it would be EXTREMELY hard to determine whether you and your cousin are actually half siblings. That's because if your dad and his brother are more like 91% or 87% or a some relatively high match for each other, there won't be enough difference, especially given that both of you have different mothers, to reliably make a determination one way or the other. You might be able to reduce the possibility that you're half-siblings as negligible, though, if you both took a DNA test, but you wouldn't ever be able to say that you definitively are half-siblings without also contributing DNA from either one of your fathers, which you should be able to get easy enough just by visiting one of their bathrooms and or nabbing a water bottle or something that one of them has drunk out of.

must be from kentucky

You could take a dna test just with both of you, the supposed cousins.

Yes, if you share 50℅ DNA you are half siblings. You just need her DNA and yours. You don't need to bring your father.