Sorry for the delay - had a minor crisis with eldest child! ( A Queen bee flew into bedroom!)
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This will not affect your husband directly as this is a claim you have made, but it may be that they ask for your actual annual income, which then may mean you need to approach your husband for details of his income, so they can see that there was no valid claim (as a joint position) so just be mindful of this, but he certainly will not be pursued for the money, so make this clear to the tax credit office, that he had no idea of your continuing claim.
Tax credits will look at this position based on facts - these are
1) Yes there has been a incorrect claim
2) You have made a full disclosure and have stopped further claims
3) You have supplied the information explaining the position
4) So make sure that you comply with all that is asked of you
5) Await the tax credit assessment of what you owe and then liaise with them accordingly.
HMRC never go to the papers, but when they pursue for a fraud claim (previously not disclosed) they can sometimes issue press releases, after a case has been to court (where they announce the amount and the outcome) but you are not being enquired into, but are coming forward to make a full disclosure so by all means in your letter state that you hope this matter will be considerate of the fact you have come forward and dealt with using discretion and taking into account that your husband is not aware of the mistake you have made.