Ask an Immigration Solicitor. Get an Answer ASAP.
Thank you for your enquiry, it has been forwarded to me to see if I may be of assistance.
Her right to citizenship would be likely affected , if the husband was to say ( with supporting evidence) that the purpose of her marriage was fraudulent. That is, that they only got married for the purposes of her obtaining her UK citizenship. Furthermore, as she has a child who is a British citizen, it is likely that if she were required to do so, she could apply to remain in the UK on that basis ( that however is not relevant for her purposes as she currently has her British citizenship)
I would therefore not worry about the husband and report any threats or blackmail to the police.
Alternatively, she could seek the services of voluntary or organizations across the UK that assist women such as herself who may be in abusive relationships. It is best to report this now so that it is on record that he has been threatening and abusing her for sometime.
I hope this answers your question if so kindly rate my answer positively so I can get credited for my time. If however you feel that the answer does not cover all the points raised in your question please DO NOT rate my answer negatively I will be happy to answer further question until you are satisfied with my answer.Kind regards
Are the children currently UK citizens?
No the children would not be affected. In any event, their citizenship is likely based on the father's citizenship and not contingent on mothers. As such, it is unlikely that anything that affects the mother, would affect the children.
Thank you for your feedback.
I apologize for my delayed response. I did not realize your further question. Please see below link in relation to that application:https://www.gov.uk/uk-family-visa/parent