No one has to live in abuse. Its a horrible crime to tell any woman or man to stay in an abusive relationship. The abuser usually starts in on the children too and what kind of life is that to have your children grow up in? The spouse being abused should leave for her or his safty and the children. More then likely the abuser is a drinking, drug user or having an affair...all three are a fourm of adultery too. She doesn't have to divorce him...but she does have a right to protect her self and her children. Women are killed all the time due to abuse...and I find it outrageous that churches actually tell these women they have to stay and endure this.
Studies also show the chances of these men (or women) ever changing are extremely low. They rarely do. It literally takes an act of God for them to change. If you study the bible you see adulterly is considered anything put above God. If rage and anger is put over God...that is adultery and the woman has a right to divorce him.
Its something she needs to pray about and let God lead her on...but she has GOT to get out of that situation. You can't lead someone to God who is smashing your face in.
I wouldn't consider being hit once, ongoing physcial abuse. There are many different types of abuse...including emotional and mental abuse. God wants us to live in peace...not endure a lifetime of abuse. If a woman or man is being abused, they cannot serve God in anyway either...they are too busy just trying to survive.

Its a horrible horrible way to live. I wouldn't wish it on anyone.
Psalm 106:39
They defiled themselves by their evil deeds, and their love of idols was adultery in the LORD's sight.
Isaiah 57:8
Behind closed doors, you have set up your idols and worship them instead of me. This is adultery, for you are loving these idols instead of loving me. You have climbed right into bed with these detestable gods.
Ezekiel 23:37
They have committed both adultery and murder--adultery by worshiping idols and murder by burning their children as sacrifices on their altars.
What is an idol? Does it have to be some false god the abuser is worshiping? Isn't money an idol? Material things? Anything we put above God is an idol...that includes those that woship their own anger and use it to control and hurt others. Many children that are abused and killed by a parent...that parent is usually abusing the other parent also.
1 Corinthians 7:15
(But if the husband or wife who isn't a Christian insists on leaving, let them go. In such cases the Christian husband or wife is not required to stay with them, for God wants his children to live in peace.)
God wants us to live in peace.
In many cases of abuse if the spouse leaves to keep themselves and their children safe...even if they do not divorce the other...eventually the other spouse will find someone esle to control and get the dirvoce themselves anyway.
God bless