Sad day

Today is a very sad day. This morning we had to make the decision to put our beautiful cat Lucy to sleep. Late yesterday afternoon I found her laid in the kitchen in an odd position and in an odd place I thought she looked like she had collapsed and was really worried about her. She did get up and eventually walked but was very slow and kept sitting down so I was very worried. After a while she got up onto the sofa and sat on my knee so I thought maybe she was ok and I was just worrying about her.
We have been worried about her recently and keeping a close eye on her as she went blind at the beginning of the year and was still getting used to finding her way around. The vet thought this was due to raised blood pressure causing her retinas to detach suddenly because she suspected she had hypothyroidism. Other than this and a bit of arthritis she thought she was ok for her age  so didn't want to prescribe any tretment for the hypothyroidism unless she showed any other symptoms due to her age.
She suffered a setback on Sunday when she must have bumped into something while we were out shopping and ended up with the equivalent of a black eye. It was very runny and sticky when we came home so we bathed it and took her to the vet on monday which is where we were told what must have happened. She had been getting a bit lost and confused occasionally and when I told the vet this she said it was the start of dementia and she sometimes would forget and lose her map for where things were in her mind for a little bit and so this was probably how she had bumped into something and hurt her eye. We were given anti inflamatory eye drops for her and she was ok for a few days until yesterday.
Later on yesterday after she had got down from my knee she was walking round the room when her back legs gave way and she fell over, she laid where she was for a while and after a little while she would get up and walk a bit but then would either sit down for a little while or fall over again, her back legs would give way and her front legs slid too and she didnt seem to be able to correct them. We rang the vets but couldn't get an appointment until this morning so we had a worrying evening keeping an eye on her and wondering what was wrong with her.
She spent most of the evening on her bed but just before bedtime came in for a sit on Pauls knee for a little while. Everytime she got up we thought ooh maybe she'll be ok but still worried things werent right. I also noticed her eye had gone red which worried me so we didn't put her drops in just in case they had upset her eye and because we didn't want to distress her doing it. When we put her to bed last night she got up to her litter tray and for a drink without collapsing but she sat down a few times on the way back and was wobbling by the time she reached her bed so we knew she still wan't right.
At the vets today we explained what had happened and she put her down on the floor to see her walk but Lucy couldn't stand, again her legs just splayed out from under her. The vet examined her and said she thought it was a neurological problem and judging by the way she placed her front legs on the table it was quite high up and affecting her front legs too. She said the lession was probably in her brain and when she looked at her red eye she said it was blood in her eye and she had bled into it. It was heartbreaking news for us as she said there was really nothing they could do for her now and the best thing for us to do was to let her go to sleep. She said she wouldnt have been aware of what was wrong and so wouldnt have been in pain but there was really nothing they could do for her now. I don't think she would have lasted much longer and the vet said it would be best to let her go peacefully now and not let her suffer. I picked her up and she cuddle into me and the vet put her to sleep in my arms.
I'm sorry if this has been upsetting for anyone to read. I just wanted to put it down somewhere as we are heartbroken, she's been with us for 19 years, most of our married lives and we'll  miss her terribly.