Internship update

I have verbally and contractually agreed to an internship with Philadelphia Photo Arts Center. I'm quite certain this is a full time position. It is a no-pay internship and she'll probably have me working 3-4 full days per week. Since this is full time, I'm not looking to apply anywhere else. I just have to figure out how I'm going to tell the other places I'm applying to that I don't want to work with them anymore....