It's really common to get an inflamed uretha after Nitrofurantoin; I've had it a few times and tend to get it, and it's listed in the common side effects. Essentially it's a really good antibiotic for clearing infection, which it sounds like it's done, but it's strong and it can leave you feeling a bit rough.
The best way to recover is going to be to stop taking antibiotics, which will make your body feel even more under attack, and to try and calm. Would you be able to manage relaxing in a bath when your partner is home? That might help. Be gentle wiping after the toilet and only go when you need too; it's easy to convince yourself that you need to go all the time (I'm still battling that after taking nitrofurantoin in December).
Propanolol is a godsend for anxiety but can worsen constant anxiety because it creates a bit of a spiral; and if you're not sleeping, that's going to worsen your anxiety too. What will help you to feel a bit less anxious? Could you plan a really busy weekend day so you have no time to think about it?
It is really, really hard; and your mind is better at "tricking" you into feeling that you've go symptoms than you'd ever expect. They feel absolutely real - they are real, other than that they are being caused by the anxiety, and not an infection or illness. Would therapy help you, have you attempted that before? You might need to go private to get seen quickly though, unfortunately.