You should ask at a forum where there's other people who have come 'out of the closet'.

Part of me says you should just tell them and see what happens, but this may be a lot harder than I imagine it to be and sadly, not all parents can accept the sexual orientation of their children. It is hard for you to judge, impossible for us to judge, how accepting they will be.
It also depends on how much support you still need from your parents.