As a DM, I had a player tell me once they did exactly as you described.
"I feel bad. I put myself at negative HPs because it would have outright killed me instead of letting it outright killing me. I am sorry"
You know what I told him?
"Thanks for letting me know. Every once in a while, that's perfectly OK."
And you know what? It is. And it is because the larger picture is that you had fun, the other people had fun, you weren't blatantly cheating and in the grand scheme of things, it didn't make a huge difference.
Sure, it means you aren't lawful good, but if you tell someone that they look great in that hideous dress they are wearing, then you already disqualified yourself anyway.
The trick is to find the fine line where you and your DM are OK with it, knowing full well that it happens here and there.
Because after all, having fun is the larger part of what you are doing.
Hell, if the 'Mask' can have a three minute death scene before dying off, you should be allowed to also!!
=)
Final statement: Not everyone will agree with what I have said. I know this. =)