Since you are the only one working and has unstable income, it is best you are conservative. Can you guarantee you still have a job tomorrow? Will you be the next victim of retrenchments? What if your income goes from $200k pa to zero?

So it is best you just buy a 4 room HDB flat and pay it in full. So that you don't have to worry about a place to stay. Keep the rest of your wealth in cash as you have two small kids and wife to feed. If you lose your job, at least you have cash to feed them.

To retire, when your kids move out, you can rent out your rooms to FTs. You can also ask your kids to give you monthly allowance of $1000 from each kid.