I know how you feel guilty about relapsing, and I think the first thing that you have to do is forgive yourself. Everybody makes mistakes - and I've relapsed before when I used to SI, so afraid to tell anybody, and the guilt eating me up inside... but afterwards I wound up admitting to my parents. I can't tell you who you should tell, and in some ways I'm not sure that it matters who, but if you can take a leap of faith and trust somebody enough, you telling somebody else would really help with this guilt in your heart. I'm so sorry that you're going through this, and feel free to message me if you ever want to talk about this more, or anything in general