I did the same exact thing. I couldn't manage to fix mine I tried filling the holes with solder then JBWELD I couldnt manage to get at all the damage that I had done and wound up buying a new rad.

I know that they make radiator patch stuff that you pour into a radiator and the heat melts the little metal flakes and patches the rad. This might be hard as it will probably get stuck in your pump and you might not have enough heat to melt the patcher.
let us know if you manage to fix it.
Jordan