Get a solicitor asap. You need proper legal advice but the fact is that if he's paid part of the mortgage all these years, he may be entitled to half of proceeds.
I got this online
f the marriage was short, say under 3-4 years and there is sufficient equity in the house, the court may order that the deposit is returned to the payer.
If the marriage was longer then the court will start at a position of trying to achieve equality, unless there are good reasons to do so, especially where there have been children born in the marriage. There are no hard and fast rules, but the court is governed by s.25 of the Matrimonial Causes Act 1973 ( as amended) which says it has to take into account the following, after it has considered the needs of any children under the age of 18 or in full time education.
(a)the income, earning capacity, property and other financial resources which each of the parties to the marriage has or is likely to have in the foreseeable future, including in the case of earning capacity any increase in that capacity which it would in the opinion of the court be reasonable to expect a party to the marriage to take steps to acquire;
(b)the financial needs, obligations and responsibilities which each of the parties to the marriage has or is likely to have in the foreseeable future;
(c)the standard of living enjoyed by the family before the breakdown of the marriage;
(d)the age of each party to the marriage and the duration of the marriage;
(e)any physical or mental disability of either of the parties to the marriage;
(f)the contributions which each of the parties has made or is likely in the foreseeable future to make to the welfare of the family, including any contribution by looking after the home or caring for the family;
(g)the conduct of each of the parties, if that conduct is such that it would in the opinion of the court be inequitable to disregard it;
(h)in the case of proceedings for divorce or nullity of marriage, the value to each of the parties to the marriage of any benefit . . which, by reason of the dissolution or annulment of the marriage, that party will lose the chance of acquiring.
You can see the legislation here
www.legislation.gov.uk/ukpga/1973/18/section/25