I must say I can't BELIEVE the abuse the original poster is taking here.
Considering people have already admitted to leaving their hamster for more than a week and it's been fine, and the fact that it seems pretty clear it got Wet Tail (which in my experience it's extremely difficult to sort out anyway since the hamster is likely to die within a day of symptoms appearing), it's a shambles that so many uneducated people are already giving this person heaps of abuse.
OP, you said your hamster was a year and a half old, but most Syrians can only expect to live to two or three years anyway, so I'm confident that (other than this week of course) you treated it great.
I'm also annoyed at the people who are slagging them off for saying the hamster was their best friend. Many people have loads of friends but still see their pet as their best mate because they can tell it all their secrets and they know it'll never tell anyone. It may sound sad, but unless you've had a pet you won't understand the bond. So you've got no right to make fun of them, especially at a time like this when they've just lost that friend. You should be ashamed of yourselves, but I have the feeling you won't be. So be it.
Finally, Margerie Dawes, if you can't understand why you've been negged by so many people then it should really be you who's getting the abuse and not the OP. The lass/lad's hamster died and they're crushed about it, so you proceed to tell everyone how it's just an animal and how you put bleach in a hamster's drinking water. That's just beyond sick.
The difference between you and the OP is that the OP feels terrible about what happened and, more importantly, the death may not have been their fault but may in fact have been Wet Tail which they'd have been unlikely to cure even if they'd been there watching it 24/7. However, you went out of your way to deliberately kill your hamster because you were "bored" with it, which means it should be you who's getting all the abuse on here.
Guys, check the facts out before having a go at the OP. Yes, it's a bit daft leaving a hamster for a week but nobody even knows the circumstances surrounding this. The OP has already said that they usually check on the hamster every night and morning, but that they hadn't been in their bedroom for the past week, so it seems they've been staying in another house or been on holiday or something and their mind's been on something else. Yet everyone seems to have missed that. It's not like the OP was going to bed every night and completely ignoring the hamster cage facing them.
And for the people saying "I hope you don't have kids" and "what if it was a baby" - for God's sake people, grow up. There's a world of difference between the two and I'm sure the OP isn't that stupid.
All I'm asking is that you all check out the facts before kicking the OP while they're already down, because from what I've seen it seems likely that (given it was a Syrian and the symptoms seem right) the hamster died of Wet Tail and there would've been very little they could have done about it anyway.
OP, PM me if you want some proper help and don't keep putting yourself down, because it may not have been your fault, regardless of what you're getting told on here. You need sympathy at a time like this, not people queuing up to have a go at you while hiding behind the glass wall of the Internet.