The timing chain broke, the now non-synchronized valves were smashed by the pistons, some valves bent, ruining their guides, some rocker arms will need to be replaced the cam shaft(s) may have been broken. Most of the damage is in the cylinder heads which can be rebuilt or bought as rebuilt. Metal in the oil pan sounds a lot worse than it is, don't let that discourage you from fixing this engine.
I've seen $3,200 repair bills for older, 420 V-8s when their chains broke - but those broke after 120K miles.
For this to occur after only 61K miles is unconscionable, IMHO. Suggest you call the MBUSA Zone office and discuss it with them adding that you have all service records.
If M-B doesn't help you, see:
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and
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for the cost of rebuilt cylinder heads (plus installation labor).
Still, horrible as it is, it's much cheaper to fix this engine than to buy another car.