There is a big difference between offering someone forgiveness and choosing to forget what they have done. When the Pope talks of forgiving domestic abusers, I imagine he is talking about those who are genuinely seeking forgiveness, and highly doubt he would encourage a person to put themselves back into a dangerous situation.
It's one thing to forgive somebody for the things that they have done to you, but it's quite another to put yourself in the position for that person to hurt you again. It's fine to forgive, but generally it's best to just remove yourself from the situation and start over somewhere else.
Victims of domestic violence should not simply return to their abusers, even if they do forgive them. They will end up being abused again, and in many cases the abuse gets worse. Perpetrators of domestic violence need to undergo serious therapy before being trusted in a relationship again, and the victims should not be manipulated by requests for forgiveness that are not genuine.
No, they shouldn't go back, but forgiveness is a key component of Christianity. Forgiveness doesn't mean the victim has to go back to the offender. The victim should forgive the offender by telling them that they forgive them, after the offender has asked for forgiveness. Going back shouldn't be considered.