Help…cat diagnosed with HCM?

We rescued our (now 6 months old) kitten, Hershey, 2 months ago from a local marketplace.
When we first brought him in, he had mange (a kind of skin disease) and a serious hairball problem. We took care of him, with frequent trips to the vet, cured the skin problem, had him vaccinated twice, even had him tested for FLV and FPV. Everything turned out negative.
We were sure that we'd done the best we could for him to be healthy.

Then we tried putting him up for adoption (something we do often, we rescue lots of kitts), but no one wanted him. And then we made the final decision, to keep him, as part of the family.

Things seemed fine until a few weeks back, when I noticed that his breathing was getting harder than usual. Took him to the vet, and they suspected a respiratory infection, and recommended antibiotics.
But as time progressed, Hershey's condition only got worse. He started breathing HARD, with his mouth open…and his belly started to look bloated. Nothing seemed normal.

Two days back, we brought him to the vet again, and after an x-ray, our vet told us that Hershey had fluid all around his lungs and abdomen area.
To get a clear idea of what was causing it, we took him to another vet for a Ultrasonography test, after which they confirmed his current condition, HCM.

His ventricles were huge and swollen, pumping blood twice as fast. And a back-flow of bood was occuring, causing tension to the arteries and lungs. This in turn, was causing fluids to 'diffuse' out into his body and tummy, because of the extreme pressure to the walls.

The vet drained the fluids by getting a needle into the chest and tummy (no sedatives, and Hershey remained quiet…i'm not sure if he was in pain). And prescribed a few pills, which he'll have to take twice a day, for the rest of his life.
He told us that the fliuds will keep building up, and that Hershey would have to keep coming back for needle draining (this is what bothers me the most, he's got pierce marks around his tummy and chest…i can't imagine how it would feel to have a needle stuck into your chest without sedatives etc).
And the last thing he told us was the possibility that Hershey may not live past the age of 1. That this condition was a birth defect and has taken over him at such a young age. His arteries are so small that chances of blood clots are high too.

Hershey returned yesterday. He seemed happy to be back, ran around for a bit, with his playmate of the same age. It almost made me cry to see him so happy, knowing that it was only temporary, and that the condition would return.
Today, I noticed him getting a little quiet and sedentary again. Not as bad as he used to, but it's starting again…and his tummy's swelling again.

This is all to painful for me to watch and handle.

People never wanted him because the other kitts were much more beautiful. But this fella had the sweetest personality out of them all. He even made the vet smile, kept rubbing his cheeks on the vets face while he was busy checking the ultrasonography results.

This is just HARD.

For me to handle the medical expenses on a long term…and to wait for him to eventually die. He hates meds, and it really bothers me to think he'll have to go through the same procedures again with the vet.
The vets suggested that we'd probably want to consider putting him to sleep, to relieve him of this condition. But it was only a suggestion, and they said that the decision making was up to us.

Help me…do I wait for signs of him suffering before relieving him…or do I take action now, knowing what lies ahead for him? My heart feels torn in two.
Is euthanasia painful? What will he be feeling when they do it? I don't want him to feel ao much as a needle prick on his body when they do it. Do they sedate kitts first before putting them down?

And will Hershey forgive me?

I need support from all of you, I need to know that I can forgive myself if I ever proceed with this decision…please help??

Here a picture of him from back when things were alright:

http://i808.photobucket0o0com/albums/zz1/V…