So the other day, my car would not start, and lo, the clamp on the negative terminal had snapped (Update - it didn't snap. It fracking melted. I just looked at the old clamp.). I got a new clamp, and that's not the problem. The problem is I can't connect it. When I touch the cable to the terminal, there are sparks, the terminal is pitted and there is melted lead (I assume from the terminal) dripped down the side of the battery, and the starter motor turns over.

Is there anything I can check with a simple voltmeter, or should I just take it to the mechanic right now?

The two truck driver from the night it snapped told me I could have just started it with a jump and driven it home. Does this sound like a good idea at this point, or should I just have it towed so I don't destroy both cars?

More info: My car has been experiencing problems for months now (and I've poured a lot of money into diagnosis with no result) so I guess I shouldn't be too surprised at this latest development.