I dont care if you're not looking for advice, I'm going to go all big brotherly on you and give it to you anyway.
Cancel the appointment.
It will only make you realise that sex alone won't make you happy, and highlight the fact that you have an emotional void in your life that can only be filled by making meaningful (even if they are casual sometimes) connections with people you have chemistry with. If somehow you come out of this free of disease and/or self loathing, any future partners you have WILL be pretty put off or disgusted by the fact your dick has been in a hooker and that you paid for a shag, if for whatever reason you don't tell them, you're then keeping it from them/lying which will screw things up. In a few days/weeks/months you will still be lonely and unable to find sex, but now you have a history of sleeping with sex workers, not exactly attractive or good for your self worth. There will be plenty of moments when you look at her and know she's only doing it for the money and probably pittys and dislikes you. Talk about a boner killer. You are far better developing your social skills and learning to talk to women, becoming an attractive proposition in your own right. It will help your self esteem rather than hinder it and sex won't be hard to find ever again.