Sara, Eve, May

Sara, Eve and Mary are identical triplets, they are 25 same age as me , I have know them since high school. Sara is my wife of 5 years now and we have a child together, our 3 year old daughter Ellie. Recently I noticed something wierd, Sara had a small mark on her her hand from gardening , i didnt say anything , later that night i noticed the tiny rash was on Eve's hand . so while Sara was a sleep a put a tiny black dot using a perment marker on the back of her neck. over the week first it transfered to Eve athen a few days later to Mary. A horrible realization hit me . which one was my wife