I have found in the past that rejecting clients makes them want you more, sometimes to the point of obsession. I once told a guy not to come again, with the result that he would turn up unannounced, ring the doorbell, and initially try to sway me with flowers, champagne etc., then progress to kicking the front door in a rage, yelling that his money was as good as anybody elses'. The thought that I'm perfectly entitled to decide who to see didn't enter his head. Others have found it similarly difficult to accept, walking up and down outside my house, peering across the road, phoning, sending endless emails etc. When you think about it, if a guy can't even get laid when he's prepared to pay for it, it must be devastating for the ego.
I now find ways of making them reject me, wherever possible. The best way is to up the money until they duck out. In your case, I'd simply say you have developed feelings for him, and stupidly mentioned it to hour other half during a drunken moment. Your other half has a problem with jealous rage, and has already gotten into a fight with a former regular of yours, when he came to see you too often for comfort. The police at the time let him get off with a warning, but a repeat performance might land him in court.... blah, blah.
No matter how obsessed your punter is, the prospect of having to be a witness in court against a sex worker and her angry other half will pour cold water on his passion.