Am I doing the right thing?

[iamloading]

We have an appointment to put my little cat to sleep in two hours and I can't stop crying.
I've had to have cats PTS in the past but it's because they've gone blind or been seriously ill so it's an easier decision.
He is 14.5 and hasn't been happy since I moved house 8 years ago to be honest. He has a cat flap, multiple litter trays, feliway diffuser, tried the urinary food, no other pets.
But basically he wees everywhere. We've had to have all the doors to the bedrooms shut for years now or he wees on the duvets. The carpets are covered, we have actual rivers in the garage. The whole house stinks.
All the presents under the tree have been weed on, and now he has started pooing too.
In the last 12 hours we've had a poo on the landing, a wee in my daughters bed (didn't realise and put her to bed so she was covered in wee too) where I left the door open for less than a minute to grab her some clean PJs, a wee all over our shoes which are 20 cm from the litter tray.
We just can't go on like this but I feel EVIL

Anyone?

Has he been checked for any health issues including blood tests?

Yes he has. There's nothing they can find wrong with him without doing scans etc. however as an old nervous cat I'm not sure I want to start putting him through scans etc

I had one of my dogs put down for a similar reason at a similar age. I was in floods of tears at the vets but I couldn't carry on and he would wee in our other old dogs bed too so she would end up sleeping in it.

I have a very nervous cat; however, she is prone to overgrooming. What has finally put an end to overgrooming was Feliway plug ins together with Zylkene. This combination stopped the last episode of overgrooming which lasted over a year. Have you tried something like this?

I think if you've tried absolutely everything. And he's still that unhappy. It's the right decision. With that hostility he's unlikely to be rehomed quickly. If at all. Very sad though it is. It's better than a life if misery and fear.

My cat went through a very bad phase of peeing everywhere including on my bed , my sofa , the carpets etc . When I watched him pee , he looked like he was struggling to pee so I took him to the vets , lots of scans and blood test reviled he had a partially blocked urethra he was put on various different meds and it has improved but he still has the occasional accident once a week as apposed to tow or three times a day.