If he sends you inappropriate text messages, show them to your parents. Showing them evidence might help them believe you. If he says stuff to you in front of your friends, have your friends go with you to talk to your parents. You should also go to the police with the text messages and pictures and get a restraining order. Do whatever you have to do to get this guy away from you. You could also use a tape recorder and record inappropriate things he says to you. The more evidence you have, the better. Never be alone with him. Do not go to your sister's house. Do not let him into your house when you are home alone. Protect yourself.