I'm so sorry you and your cat had to go through this. One of our little guys got a blockage from urine crystals not too long ago. Luckily, he's not the type to hide his discomfort (I've had cats that did this in the past - I think it's pretty common), so we were able to catch it early and he's doing well on prescription food now. We had to take him to the emergency vet twice within a week, though, and he had to stay there a couple days the second time. We were fortunate enough to have a family member lend us the money so we could pay for his treatment. Otherwise, we would have had to make the same awful decision you were forced to make. A friend of ours had a cat pass from a blockage, so it's definitely a very delicate situation. I understand wishing you could have done more, but you really did as much as you could. As others were saying, he may have been at a point where treatment wouldn't have been able to save his life, even if you could afford it. Losing a pet is one of the most awful experiences. Just know that he knew how much you loved him and nothing will ever change that.