My bitcoin software is Multibit 0.5.1

I recently accidentally sent much more BTC than I have in my wallet, several hundred times more. I know how this happened and will avoid it in the future. Because of this, I have an empty wallet, and an unconfirmed transaction that isn't completing. It's also raising another problem. What will happen if I get more money into the wallet? Will it be fed to the huge attempt to send BTC? Will I need to make a new wallet, and abandon this one?

Thank you.