P0430 code (hole in Exhaust Manifold)

Hi again. Thanks for your reply. Attached you find the pics that you requested, the first one being of my driver's side exhaust manifold that had the big hole in it where the circle is, as you can see, I tried to patch it but still leaks, along with the second pic of my catalytic converter, which please note that when I first found the hole in exhaust manifold my cat did not have the copper toned color on it as it does now in pic. All the blue arrows point to where there were leaks, as you can see, they are mostly in the seams (or where pipes joined together. And all the junk on it is where I tried patching them.
But now since then, another problem has occurred. I lost my keys for about a month so I couldn't drive it, then last week, I called over a lock smith to come out and re key my ignition and when he finished doing so and programming it with his little computer, I drove it just across the street to laundry mat, and it drove and sounded just like it did before (exhaust leaks) but now when I got in it and drove back home (right across the street) it acted real weird when in reverse and then started making a loud engine sound I never heard before until I got home and shut it off. I am thinking that that is when my catalytic converter went out and turned the copper color it did. Anyways I decided to check my oil and transmission fluids as I always paid close attention to regularly and found that my coolant reservoir was empty, and my oil was now milky. But what I do not understand is how did a get a blown head gasket while my truck just had been sitting and it never once overheated? When the truck first was sitting the oil was fine. No water in it. What do you think is the reason behind all of this and what should I do? Please help. First the big hole in exhaust manifold, now blown head gasket and is there anything that someone could have done to it while it was sitting to cause the water in my oil? Please help me!