Me and My child's Residency

Hallo,

I and my husband are German residents. My husband is a blue card holder.  I was married to him and got a German residence permit.  I and my husband are Pakistani nationals.  After marriage, when I got pregnant, my husband lied to me and brought me to Pakistan and when I came back to Pakistan, I found out that my husband had a third marriage with me.  I filed a case against him in Pakistan. In the court he accepted that he had cheated me.  We haven't separated yet.  I don't want separation because of the baby. My husband is not taking us with him to Germany.  He says stay with my parents in Pakistan. He was living in berlin germany and I am and our son is in pakistan. I want to go to Germany for our son's future.  I want to get his German visa.  I don't understand what should I do please help me.    Can I leave my son with my mother in Pakistan and go to Germany to complain about my husband? Will it be safe for me and my son to do so?

I am looking forward for your kind responce 

Thanks,

Mariam moin.