I would like to have a sister like you. My brother wouldn't throw me a rope if I was drowning. You are really in a difficult position. Your sis would never talk to you again if you told your mom.

If you don't tell your mom and she is pregnant or diseased, how would you live with yourself?

Being a little devious myself, I would call the school and speak to her counselor. Have him talk to her. He/she can't tell her who called. Really, you don't even have to tell him/her who you are.

Even if she found out you did save her, she would only hate you until she got smart enough to realize how much you helped her.

Would she be a good mother?