Sounds like the water pump leaked/failed (it is located down on the
passenger side of the engine which is where the coolant seemed to come
from) and mechanically seized, which tore up the timing belt (timing
belt drives the water pump as well as the camshafts).

It happened to me on my 1999 Camry LE4 (now at 132,000 miles) a few
years ago, just before the warranty expired.  Died without warning on
the way home from work; I coasted to safe spot on the shoulder, shut it
off immediately, and called for help.  AAA towed it to the dealer, who
repaired it at no charge under warranty, so I never learned what the
ultimate cost was.

Sometimes you get some warning ahead of time via dropping coolant level
in the see-through reservoir tank, as tiny leak or weepage from pump
worsens gradually.  Other times I think it is more sudden.  Always seems
to play out the same way :-(

Mechanic will also need to listen to engine once they get it going again
to make sure no noise or other symptoms indicating internal damage from
the overheating.  However, if you didn't try to keep it going after the
failure occurred you're probably going to be OK (I was fine, no harm
done).  Your engine is noninterference type so when timing belt fails,
Mr. Piston doesn't meet Mr. Valve :-)

I'm going to make a guess that it will be several-few hundred $$ to
disassemble, replace the water pump, change the timing belt, reassemble,
refill with coolant mix, check operation, etc.  While they're in there,
the mechanic will probably replace the timing belt tensioners and maybe
some seals if he feels they need it.  Most of the cost will be labor to
get at all of this stuff.  The parts themselves are not necessarily all
that expensive.

Since warranty is most likely not an issue for you (1998 model, 127000
miles) unless maybe you have kept some sort of super-extended plan on
the car,  I would get phone estimates from several shops just to have
for comparison with what your mechanic proposes to charge (make sure you
are comparing apples to apples with respect to tha actual work involved
in each case).  But when the car is sitting there in its present
broken-down condition, it's hard to really shop around unless you own a
tow truck too.  Fortunately this is something a good independent
mechanic (or maybe even an advanced do-it-yourselfer with the time,
garage, and tools) can handle so don't feel at the mercy of the dealer's
shop.

Good luck !