9 year son affected by Dad's imprisonment - from a Mother

Hello. My husband has been sent to prison. We have a son who is 9 years old. He has been sent to prison for selling drugs. The Police smashed our house door in which terrified us. My son has started bed wetting and is screaming and having nightmares. He does not want to see his Father and will not speak to him on the phone when my husband telephones from prison. 
He tells me he hates his Father and that he is being picked on at school. I have found letters written by my son to his Father in his bedroom and there are some nasty words in them. I did not know my husband was selling drugs. He has a very profitable clothes company and I thought that his business was doing very well. I did not know that my husband was selling drugs to make more money. 
I feel very ashamed but I must stand by my husband as we are a very close family but my son will not speak to his Father. I am not getting any help and feel very alone. 
My son has refused to go to school this morning because he is saying that his Father has made people pick on him and that his Father is a very bad person. I am lost and very worried for my son. He was once a very happy boy.

A list of support groups in the lady's area has been forwarded on to her.