There is an important issue of forgiveness in families where abuse is involved: in many cases the abuse is ongoing and chronic. It may be that one person's role in that family is simply to take the abuse. If the dynamics are that the family doesn't want to heal this when the person wishes to move on and grow, then what picture does forgiveness take? Unreasonable demands reopen the wounds of abuse. In that case, the words "turn the other cheek" may take on meanings I don't think intended by Jesus -- to allow ongoing abuse to continue as if this is the sole purpose of one's relationship. I think forgiveness must be a concept that our relationships are mediated by God: we don't take revenge, we take things to God and "give them up" or "let go" which is closer to the Greek, it seems to me. But that doesn't mean we might not need to keep our distance or limit contact, something the other family member, unwilling to change, may take as a hurtful response. I think this is such an important issue and it seems rarely addressed.