Is it obligatory to take back the first wife, knowing that she was a victim of touch ( demonic possession) and was not responsible for her actions, and that the husband has young children with her, and that he has married another woman?

You are not obligated to take back your wife, but if her ill-temper is due to what you mentioned, then you should take her back, unless you hold a grievance against her regarding her religiosity or character. This is further emphasized if you have children with her.