Sigh. If only the plane ride to Singapore's East coast restaurant row was 2 hours instead of 24 hours! Sadly, I haven't found a place that offers authentic Singapore chili crab here in DC. Perhaps you can call the owners of Malaysia Kopitiam and beg them to do a special Chili Crab dish for you:
Malaysia's chili crab is similar to Singapore's chili crab (Malaysians will claim that their version is better).
If your travels take you to BOSTON, MA, the Penang location in Chinatown does THREE different crab dishes - I believe the last of the three will be similar to your beloved chili crabs. I don't know why the Penang location in DC don't seem to have it on their menu - I suppose each Penang location is a separate owner/franchise. The Penang in Boston is particularly good, IMHO:
(*) PENANG HOUSE SPECIAL CRABS S.P.
Hard shell crab cooked with spicy grounded dried shrimp in authentic sauce.
(*) DRY COCONUT MILK CRABS WITH SPECIAL HERBS S.P.
Hard shell crab marinated with spices, cooked with shredded lemon grass sauce with
grounded dried shrimp.
(*) HOT & SPICY CRAB S.P.