Well,this is not crime unless you have pplied agait to get the arrears money.
It is not clear whether you are still receiving the the said maintenance order or not.
if yes then it is mistake on your part and hence you must inform the court about your employment or send a written notice to your father to stop sending you money.
if you are not receiving any money from him for long then no crime has been committed by you and you can rest assured on this.