Breastfeeding Situation!

so i had my sweet baby girl march 21...i started off breastfeeding the first day and a half, then breastfeeding and formula. i breastfed her up until today but i have also been giving her formula..more than breast. i want to fully stop giving her breastmilk but right now my boobs are leaking from so much milk! My baby is only 4 days old, how can i stop breastfeeding without causing damage to my breast? does it stop on its own? im scared because my sister had her baby and she breastfed for a couple of days and then stopped and her arm got swollen from breastmilk so she had to have surgery. im not sure about story but its something like that. but any advice on how to stop breastfeeding without getting hurt? and will my breast still leak  tomorrow if i dont breastfeed today?? when will they stop leaking?