If a man remarries all previous wills are invalid and a new one has to be made. His assets will otherwise be treated as if he died intestate. In the absence of a will it would then be up to children and wife to negotiate, who will both own half the house, whether the property is sold or whether the wife can stay in it. Hopefully children and wife would have a good relationship and reach agreement. My parents watched a house near them become totally derelict because the second wife, who did not live in the house, refused to sell, refused to let the children occupy the property and just left it empty and unmaintained for over 20 years. When she died the house had to be demolished and the land sold at site value.
When someone dies it is the will that is the legal document that decides the distribution of the estate not anything the deceased may or may not have said in life. You see court case after court case in the papers where a deceased person made verbal promises before death but never changed their will, or in one sad case I know, died suddenly while the new will was being drawn up and it is the will that holds not the verbal promises.
Harrassment is a crime. Start with the police, that usually puts the fear of God into people even more than a solicitor's letter