I have very chapped lips and they busted open overnight, looked like a cut. I am herpes1 positive. How do I know if its a cold sore or just a cut?

Diffuse vs distinct. Chapped lips usually will involve large lip areas, vs cold sores would be more or less confined to a small area. Also, if vaseline application a few times a day gives you good relief, then it is most likely chapped lips.