The fact that the interest in the property was acquired prior to the marriage and was always kept separate and never shared would usually mean that there was no risk of
your newest ex having a claim on those funds.
However the fact that there is no other capital for division is a problem here.
Your £1000 is certainly lost, and she could potentially seek a further lump sum off you based on your interest in your first matrimonial home.
However the relatively short nature of your relationship makes any claim relatively small - say £5,000 or so at most.
Whilst she herself cannot force a sale of the first matrimonial home if you are ordered to pay her a lump sum you may have to do so to raise the money.
There is no action that you can take now which will prevent that being an option.
However on balance it is less rather than more likely that such a lump sum would be ordered
Please ask if you need further details