What does it mean to repent? It means acknowledging that what you did was wrong. That you wish you could take it back, or change what happened.
What if you have done something you feel is so horrible, so bad, that people will hate you if they knew? Is it someone who truly loves you? Are you sure of how they will react? Sometimes we don't give people enough credit. Sometimes people will surprise us with how loving and accepting, even FORGIVING they can be.
My biggest weakness, that I have trouble forgiving people for, is lying to me. I would rather find out that you have just killed someone, than wait years to find out you stole something or kicked a puppy. I don't care what it was that you did wrong. I care when you hide it from me, or don't tell me the whole truth.
How can I fix what I did? Well for me, I try to ask forgiveness of the person. Maybe just ask them to do their best to forgive you, and acknowledge to them that it takes time. Come clean with the person. Tell them everything. They WILL forgive you. If they don't, they are themselves sinning. It WILL take time. Just keep trying to build the trust again.
Go talk to the people in your life. Tell them the truth. Ask for their love and support. They are better people than you may think!