Cupressus macrocarpa won't grow in a tropical climate, it needs cool summers. Sorry, but it has zero chance of survival in the longer (or even shorter!) term.

Resin

Trees need deep roots (certainly deeper than pots) and Cupressus like full sun, so keeping them indoors won't work. The Cupressus & Juniperus I've seen die all at once, which seems to be the case if you say the needles are dry and coming off.

Monterey Cypress is somewhat prone to disease and bugs once outside of California coastal strip from what I've read. One of the reasons Leyland Cypress has trouble.
Arizona Cypress is disease and drought resistant, but a tree for dry climates, as are many other cypress.
What would be a suitable cypress for OP's climate? The Mexican Cypress? (sorry exact name for it escapes me)

resin

i didnt realize Singapore was considered tropical ...

i peaked early today.. in trying to learn one new thing.. so i guess its back to bed at 1025 am ... lol ...

ken

I'm under Capricorn tropic and I had mine in well drained soil in pots, outdoors, for two years. In November, when the rains started, I moved it into the soil, in my garden. It really was a holyday plant 11" tall and came in a cup size pot. I moved it to another pot and after one year to a larger one. It was 32" tall when I planted it in the garden, now it is 40". I think good drainage and direct sun are the keys for this tree.