Lost My Poor Baby.

I'm new to the forums so hi everyone
Had a tough few months. I've lost 3 of my mice, our family cat, our family dog and one of the family rats since October but t oday I lost my baby...well not such much a baby as she was 9 years old
Probably one of the worlds most temperamental kittys who acted more like she was a Lion or Tiger than a lil domestic cat, putting the dog and the puppies in their place. She might have been grumpy and a little psychotic at times but she was also a loving and affectionate cat when she wanted to be and she was a fighter and never failed to cheer me up during tough times.
My gorgeous tortoise shell Bex:


We never really set out to have her. My mum was running a pub 9 years ago and someone who lived close by said she kept crying and they were keeping her in a rabbit hutch and wanted rid of her. Obviously kittens are hard to resist so I begged my mum to let me have her.
We don't know what would have happened to her if we hadn't stepped in and adopted her. Anyway's we took her to the vets and found out she was crying because she had a broken hip. The ball-joint connecting her leg to her pelvis had snapped and they had to remove it. I was 15 at the time but spent all my spare time looking after her and nursing her back to health.
We noticed a couple of years later that she had blood when she peed and it turned out she suffered with kidney stones bought on by stress. She had to go on a prescription diet and had a couple of trips to the vets for anti-biotics if she had a bad bought of it.
Despite everything she was an amazing cat. A bit crazy at time (but aren't all cats really?) and quick with her claws but when she wanted affection we knew about it.
Last Tuesday she didn't really move from her bed and hadn't eaten and having lost our other cat a month before after she showed similar symptoms, we rushed her to the vet.
They said she had cystitis and gave her an injection and said to take her back the next day.
We did and I noticed her breathing had been a bit jerky but the vet didn't look into it, just gave us anti-biotics and sent us home, said to bring her back on the Friday if she hadn't improved on appetite and activity.
Se picked up a bit but on Saturday night she was struggling to breathe and had barely eaten and was making strange noises when she tried to meow.
We took her to the emergency vets where they said she had a lot fluid on the lungs. They kept her in until the Tuesday and stabilised her breathing before transferring her back to the regular vets for X-Rays.
When we got her there, there were conflicting comments on her record. one saying she needed X-Rays and one saying she didn't. The vet wasn't going to do them but I was adamant that they needed to find out what was wrong so we could try and prevent it from happening again.
They X-Rayed her and did a scan on her heart which revealed her Heart was enlarged and she was going into heart failure.
They gave us some tablets to prevent fluid build up and some tablets to keep her blood pressure down, saying that she could have a few years left if she responded to the tablets.
She perked up the next day but stopped eating again.
She had an appointment booked for a check-up today to see how the meds were working.
The vet said that her condition was so advanced that they could only try to ease the problems, they couldn't cure them. They also said that she didn't really have a lot of time left and would have to be confined to one room for the rest of her life and that when she eventually did go that it wouldn't be peaceful and would be quite traumatic for her and for us.
After talking with the vet and my mum we decided that it would be best to have her put to sleep as she would have no quality of life and had given up on eating already.
Her heart stopped before they even gave her a quarter of the injection. We figured if we'd have taken her home she probably wouldn't have made it through the weekend and our emergency vets is an hours drive away so it would've caused even more suffering and stress for her if anything had have happened.
It's probably the hardest decision I've ever had to make in my life and I'm absolutely heartbroken.
I'm trying to take comfort in the fact that she's no longer in pain or suffering and that she is at peace but there's still a tiny part of me questioning whether I made the right decision even though I think I did deep down.

Sorry this is so long. I wanted to get it all out and she meant the world to me. I miss her so much already :'(