Divorced / charge placed against my property

Glen77

Hope someone can help.
I divorced many years ago when my children were very young.
in the settlement my ex got the insurance policy (around 20k at that time)
I got to keep the property as I had also provided the deposit for it and made most of the mortgage payments ( he did not work much then became registered disabled after leaving us)
He managed to never pay any child maintenance either.
At the time a charge was placed on the property which I believe was meant to be for the remainder of his entitlement ( though I could be wrong and this could have been to repay his legal aid)
I have no idea how much this charge is for and have never been sent any documents relating to it.  The solicitor who dealt with the divorce are no longer in business.
After a real struggle I have finally managed to pay off the mortgage and would like to try and get this charge removed.
If I have never been contacted about it, is it even still valid ?  I should have been entitled to know the amount and how it can be repaid or removed surely ?
Is there anything I can do about this - it seems like negligence on the solicitors part but now they don’t exist what can I do.  I don’t want to leave it as a nightmare for anyone else if I should pass away.
Any advice ?