Like we discussed in Don't trust anyone online, the Internet is full of people pretending to be someone they are not. They do this to gain your trust, so that you may share details with them you wouldn't have shared with complete strangers.
For this reason, it is always a good idea to have someone you trust know that you are talking to other people online. If you ever feel threatened or upset about something that happened online, you can confide in that person. He or she can then help you come to terms with what has happened or even confront the person causing you harm online (for example, if someone is bullying you online).
Make sure that the person you choose to trust is trustworthy. Choose your parents, guardian, aunt or uncle, teacher or even your older brother or sister. Never choose to trust friends you have met online, for they might not be who they say they are.
Trust someone in your family.