My friend is my supervisor and?

we had a shift at 630am today. My stomach has been acting up the past few days, also I've been dealing with some stressful personal issues that she knows about because she's my best friend. I decided to take today off and I gave her a fair amount of time's notice. I also had previously just worked 8 days in a row with overtime. She's really pissed at me that I took the day off saying she doesn't know why she's so nice to me, and honestly making me feel like garbage. I think its uncalled for, what should I do?