Greetings in that Divine and Most Precious Name of Our Lord and Savior Jesus Christ!
Lord have His Mercy! This is a tough one
I just want to interject this point:
These men who did this were not Muslims, they were savages misrepresenting Islam. There is a difference. This is same argument about child molestation in the Roman Catholic Church. Those priests who abuse children are not Christians, they are monsters masquerading as Catholic. We should then be very careful not to generalize these incidents across Islam (or Catholicism for that matter) as they are not indicative of the flaws of a religion, rather evidence of the evil that dwells in Mens' hearts..
When these men did this to this women, it had nothing to do with religion, Islam may serve as one pretext or another, but the root motivation is the same as it would be for any rape, attack, blackmail, violence etc etc..