Hi thanks for clarifying.
In civil cases the Claimant has responsibility for paying the Court fees at start of the proceedings and also the Fast Track fee that you've mentioned.
Therefore, if the fee relates to the case where you were the Claimant then you are liable for the fee unless you apply for remission (e.g. because you receive Income Support/JSA etc).
If the fee relates to the case where your husband is the Claimant then he is responsible for the fee.
It would be worthwhile clarifying with the Court which proceedings the fee relates to. The Court office (whose details will be on the papers) will be able to help you with this.