Damn!!! There is physically no way that a jolt from the suspension could have ripped the sheetmetal downward like that. It just doesn't make sense. Side impact looks to be the culprit. As for welding it, it obvisously won't be as strong as before, but since you didn't even notice it until now, I don't think it will be a problem for you.
It doesn't appear to be a weld in that spot, either, probably seam sealer, like you said.
But, if you're taking it to a shop, they should know what to do.
Here's a pic for the lazy people here: