Though one can't say Colombo's gay scene is thriving you can certainly find there is a gay community that lives openly but carefully.
There are no so called gay bars but there are gay parties where you will find all the amenities you left at home: gays, drags, loud commercial music, and more of what you know.
Grindr is used among gay guys and it is a good way to find out about the gay scene.
Things are different outside the city where there seems to be no middle or high class and therefore openness on the matter is not even under discussion.