Depending on where you live, some vape shops will recycle batteries (and I hope to holy goodness that they are doing so, not rewrapping them with some fancy house wrappers...) Radio shack will, some cellular places will take them, and so will places like Home Depot and Lowes, etc. Even though it's a vape battery, any place that will recycle batteries will probably accept them. I'm thinking an Office Depot might as well, but I'm not entirely sure on that one...
Sorry about your setup, hopefully you are still under the warranty period. Mods firing on their own are very dangerous, you don't want to use them. You'll need a new mod or stick, but you may want to say more about how you were using the tank, as if the tank is leaking for reasons other than the mod, you wouldn't want to have the same thing happen with your replacement. You should never have to tighten a tank that hard, usually finger tight or slightly more in some setups (but finger tight is usually enough). Is the seller an online seller or did you buy in person? Either way, I'd be asking for a warranty if it is still in the warranty period.
Best of luck, if you are planning on continuing using the tank, do post about what/why/when leakage happened, to see if we can trouble shoot. It sounds like it may've been a *connection* issue, and that is often the mod, but I'm not 100% clear on what was happening to cause the leaks, and until you know, it may be hard to use the tank.
Your other option would be to warranty the setup if it came together, and try a different setup entirely, there are some good options, pico makes some good starter setups, as well as many other brands, and you'll be able to find a tube type mod if that is what you want.
Best of luck!
Anna