If not already done, check the manner in which the house was purchased and owned:
Was it (as usually done) as joint tenants, or
Tenants-in-common.
If joint, the survivor owns it all on death, regardless of any will.
If tenants-in-common, you each own a separate half.
Whichever applies, her signature will be need on the transfer to the new owners, and on any mortgage documents relating to your ownership.
So tread carefully, make sure where you stand, get proper advice, and obviously consult the solicitor about getting any agreements signed by the ex relating to relinquishing all rights to the house or any payment relating to it now or later!