You surrender at 95% of the price you first purchased from HDB. You can appeal to HDB for loan due to divorce and a young child. HDB is supposed to judge case by case basis for divorces. If you get declined without good reason or alternative, email the minister, or quality control director or email MCYS for help/support. Or if you had the flat for a couple of years eg 4 years and very close to MOP, can still appeal to sell open market and then buy a smaller flat.
Hi... I suggest you pay a visit to HDB office to seek advise. HDB officers will be able to correctly advise you.