Physical abuse is grounds for *seperation*....not divorce.
The infamous line considered extreme physical abuse and spiritual endangerment in the same sentence....intimating apostacy is to be likened to domestic violence, but that in either case neither partner is scripurally free to marry . It then went on to quote the Bible as saying "if a man marries a divorced women he makes her an adultress" or similar wording.
I'm sorry I don't know the exact Watchtower it's quoted from, but it's fairly recent. I'm sure can be found on JW.org or Avoidjw.org.