Hi, sorry to hear what had happened to you. It is a good decision to divorce. It is very important to see carefully before commiting to a marriage. It is sad that some people treat marriage lightly. I have a materialistic friend who is married. She wears high-end branded stuff from top to toe...
The credit card debt of $50K is under both your names?
I think regarding the selling of HDB, it depends on what type of scheme it is under. Your wife also has to agree to sell the flat. It is better to ask HDB.
http://www.hdb.gov.sg/fi10/fi10322p.nsf/w/SellFlatOverview?OpenDocument