How to manage my gay life between me and conservatic family?

Well OK if there is no way you can tell your family the only thing you can do when you are around them is to be the way they want you be. I would find this very difficult if it were me as honesty is the best policy even in the strictest of families. They should love you no matter what your ual orientation was. It is hard for all families to accept at first but gosh you are all family and somewhere down the road they will get used to it and if your sister has already suspected it will only be a matter of time before the rest do to. I hope it works out for you and you do what you feel is right while trying to respect yourself and your family.