How was the agreement reached?
Sorry, how did you find this person?
what do you mean by craiglist?
It is quite difficult to tell whether what you did amounts to an offence really.
It is not illegal to pay for sex in the UK. The offences lie in the surrounding circumstances.
That said, it does sound as though they committed an offence as well.
I don't know whether they are saying she was unwilling and so was being controlled by her husband. That would fit with the allegations of domestic violence. If she was being held prisoner or otherwise unwilling then you would have committed an offence.
They do have to prove that though which is harder to do especially if she is reluctant.
Can I clarify anything for you?