Get a ceramic flower pot and place the battery in it. Then connect it to your battery cycler, to discharge it, then charge it. Do this outside, where the possible fireball won't light the house or garage on fire, and have a bucket of water handy in case it gets ugly. If it survives a full discharge then a recharge without puffing up. it's probably okay.
If you don't have the capability of cycling the battery, either find a friend who does, buy a cycler yourself, or dispose of that battery properly (in a bucket of salt water for 2 weeks) and go buy yourself another one. One house fire will cost you a LOT more than the price of a stupid battery.

btw, I hope it's not sitting somewhere out of your sight right now, where it could have already started the garage on fire!