All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad is His slave and Messenger.
Indeed you did well by seeking to observe the religious principles in dealing with your brothers in-law and we ask Allaah to make you firm on the truth.
Since your brothers-in-law are non-Mahram (i.e. marriageable) to you, then you have to observe the Islamic principles when dealing with them, like wearing Hijab covering the whole body including the face and hands. But it is permissible for you to talk to them according to the need and with good manners, without speaking to them in a soft and attractive voice and so on.
As regards sitting with them on the same table for dinner while observing the Hijab, it is more appropriate to avoid this.
We finally draw your attention to ask your husband to convince his family to give you permission to stay with your family to avoid any harm. If this is achieved, all perfect praise be to Allaah, otherwise you have to be patient and fear Allaah as much as possible, until Allaah makes things easier for you to travel to your husband or for him to return from that country.
Allaah Knows best.