It will be classed as a windfall and will have to be declared to your IVA. If you can pay your creditors 100p in the pound plus fees and possible statutory interest then anything left over will be yours.
Sharing from experiences of dealing with debt
The greatness of a man is not in how much wealth he acquires, but in his integrity and his ability to affect those around him positively.
Bob Marley. http://kallis3.blogs.iva.co.uk
To be clear: Ex has an IVA and you do not ? If this is so then his IVA will take his share of equity, after fees and mortgage redemption and your share ( presumably half) should be left alone and paid to you.
My opinions are merely that .. opinions based on experience. Always seek professional advice.
IVA Completed 23rd July 2013 .... C.C. 10th January 2014 http://foggy.blogs.iva.co.uk