HELP! Thermostat gasket/ head gasket

Starting from the beginning. I have a 2005 mustang v6 automatic that just hit 100k on the odometer. A couple months back I noticed a had a coolant leak and by the end of the week my car began to overheat. I took it into firestone and they diagnosed me with a faulty thermostat housing. At about 85k miles I did the replacement myself, I had a warranty part from autozone so i figured I'd just do it myself. In the past I was working with some older ratchets so the first thing I did was buy a new Husky set and they fit perfectly, taking a look at the housing it was already night and autozone was closed. I was anxious to try out my new rachets and possibly thought they just might be loose. There I go tightening the top bolts to the housing and the rachets work like a charm. The moment i feel like they're good enough I finish one last pull to get the rachet out AND I FREAKING CRACKED THE BOLT. I was pissed beyond disbelief and now I was forced to take it back to firestone the next day. So they rethread the hole, throw on a new housing and off I go after 700$! The next day i had a 20 mile drive to college and as I'm exiting the freeway ramp I see white smoke coming out from under my hood and my temp guage high, the housing had busted open! Firestone replaced the part again and 3 days after that it didn't blow open but i had a heavy leak. Again to firestone and long story short I was refunded for parts and labor and told that my car failed a block test and I had a blown head gasket which caused a high pressure build up and the first part to fail happened to be the housing. I've heard that blown head gaskets cause a mix in the oil and coolant or white smoke out the tailpipe and i dont think i have either of those symptoms. Is there really a possibility of a blown head gasket? What are other possibilities??? I plan on getting a second opinion real soon, what do you guys think?