98 V70 overheating disaster$$$

My V70 GLT has 80K. I have been totally annoyed with little stupid
repairs, especially the check engine light up stuff, and the oxygen
sensor/gas cap annoyances. Half the Volvo owners I query say the check
engine light is always on. I still find it hard to believe there is no
defect in that system.
Meanwhile, I drive 15 minutes to work two weeks ago. Not even a
highway drive. I get to work and horrible smelling fumes are coming
from my engine. Believe it or not, I really got no prior warnings, the
car felt fine until the smelly fumes.
The car gets towed to a shop, then to the dealer. It is a major $3000
repair, new radiator, flush everything, and a secondary blown head
gasket. They don't think that was the first thing that went wrong.
They can't even tell me what the primary defect really was. There was
oil in the coolant fluid when they first checked it.
Do I need to know what really happened? Can that much go wrong with a
car in such a short time? Did I miss any warnings? I get the oil
changed and fluids checked consistently, not always at the dealer. I
did the timing belt stuff at 65k
Where did I go wrong? Was this avoidable?
Do I have any recourse with Volvo USA or my dealer?
Are there any other message sites like this where I might get advice?