Generally speaking if you own another house that you don't live in, then the value of the house is assessed against you for means tested payments such as OPFP.
However, if this is as a result of you moving out of the matrimonial home, then they will take that into consideration. They will want to know the details of what proceedings are ongoing about the property, whether there are plans to sell it etc. They will review the situation every so often to see how it is progressing. If the house is eventually sold, then they'll give you up to six months to buy a new property before they assess the value of the proceeds against you.