My cat!

Ok so I have a cat which I completely adore! She's very good with my baby boy but is awful to my 10 year old son. She's not so friendly to strangers either, but she's gotten to the point to hiding under my bed and attacking my sons feet when he walks by and hisses at him when he tries to touch the baby. I love her to death she is part of my family. But my son is so afraid of her he locks himself in his room and it breaks his heart that he can't pet her. We've had her a year and it hasn't gotten better. Help!!! What should I do??