You have a son from your 1st wife an you married your gf. Now dont panic as maybe she is not able to understand how to interact with your son and that is why she is hesitant to meet him. Try mediation. If that is not possible then give an application in the local police station about your case and about the dowry etc. No issues as you haven't taken anything. Also explain to the police the circumstances under which you married her.
Regards