The only reason your solicitor told you, virtually in passing as I recall, that he 'could' make a claim was simply lawyer-speak to cover every eventuality. The mere fact that your solicitor did not find it necessary to discuss the merits of any such possible claim suggests that s/he is of the opinion that your twunt of an ex doesn't have a hope in hell case in law.
Don't give him the name of your solicitor and don't raise the subject of money with him at all. If he should come the old acid again simply tell him to take a hike in the direction of a lawyer because you don't intend to waste your time giving him information that he'll have to pay for he needs to hear from a solicitor.
DON'T fall into the trap of implying that he has any right whatsoever to pursue a claim against you. If you don't feel able to completely blank him should he raise the subject of finances, adopt cenicienta's excellent advice of 'my solicitor has advised me that I am (not 'could be'!) entitled to a considerable sum in respect of the business and the van' and tell him to get his solicitor to write to you whereupon you'll pass the letter to your lawyer.
Let him find out the expensive hard way that it'll cost him far more than he can hope to realise from any claim he may make to try and get more money out of you.
Expect him to turn nasty when the ow he realises that his well of easy money has run dry and that he's dependent on his new love to fund him without hope of a future windfall from you.
Now do what you should have done a couple of weeks back; text him one date on which you'll leave the garage open for him to collect his crap belongings and make it clear that anything left will be collected by your local council's refuse dept and taken to the skip, and then resolve to have no more contact with him.
Also, in the spirit of 'once more unto the breach, dear friend', if you haven't done so already, FFS change your locks.