A bucket of water (aka bucket o' caving) is one of the most important things to have on your hotbar at all times. I have mine in the third slot, only behind my sword and my pick.
so very pissed off, I had all diamond tools and had just made 10 sticky pistons (slimes are hard to find)
I wasn't even using lava, it was next to the pick and my mouse scrolled :(
That does indeed suck. Slimes are easy to farm now though, just find a swamp biome and they spawn on the surface at night (possibly in any light level).