2000 Chevy Tahoe Mechanical and Cooling System Issues

Hi! I have a 2000 Chevy Tahoe Limited. I had a minor front end collision approximately 1.5 months ago. When the repair shop called to say it was finally done, I was relieved! I had to drive out of town the very next day. That trip was approximately 375 miles (roundtripHi! I have a 2000 Chevy Tahoe Limited. I had a minor front end collision approximately 1.5 months ago. When the repair shop called to say it was finally done, I was relieved! I had to drive out of town the very next day. That trip was approximately 375 miles (roundtrip). The whole way there, my truck ran horribly, overheated continuously and steadily got worse! When I returned home, I parked it not wanting to make it any worse. I had to drive it again, to the pharmacy about two weeks ago. That was about a 5 minute trip from my home. When I returned home, my husband opened the hood to check the water in the radiator, added water and black "gunk" poured out of the radiator. It also came out of the reservoir. It is blowing "white" smoke out of the tailpipe. I called the shop, angry and they told me to bring it back in. I received a phone call the next day, telling me that there is no leak in the radiator but that the water pump is bad, that the intake manifold gaskets are bad, there's water in the catalytic converter, and the list goes on. Needless to say, I was fuming!! (My husband and I just replaced the radiator, hoses and water pump approximately 5 months ago.) This whole mess was supposed to be covered by the other driver's insurance and long story short, my insurance hadn't even contacted them! Therefore, all these repairs would be on my dime! (And I had to pay $500 deductible for the body work that was done!)
Sorry for the long story but I needed to explain in order to get to my question. I am wondering if this is going to be a costly repair and also, if you feel it's the intake manifold gaskets, or instead, the head gaskets? When I returned home, my husband opened the hood to check the water in the radiator, added water and black "gunk" poured out of the radiator. It also came out of the reservoir. It is blowing "white" smoke out of the tailpipe. I called the shop, angry and they told me to bring it back in. I received a phone call the next day, telling me that there is no leak in the radiator but that the water pump is bad, that the intake manifold gaskets are bad, there's water in the catalytic converter, and the list goes on. Needless to say, I was fuming!! (My husband and I just replaced the radiator, hoses and water pump approximately 5 months ago.) This whole mess was supposed to be covered by the other driver's insurance and long story short, my insurance hadn't even contacted them! Therefore, all these repairs would be on my dime! (And I had to pay $500 deductible for the body work that was done!)
Sorry for the long story but I needed to explain in order to get to my question. I am wondering if this is going to be a costly repair and also, if you feel it's the intake manifold gaskets, or instead, the head gaskets?