I'm in a similar situation, except the family is very anti-spiritual (almost an opposite to yours
) sort of thing.
I'm slowly talking to them about more and more things.
There is one thing I will tell you though. You will always feel depressed and trapped until you align yourself with what you believe.
You have to start being yourself, even though it will be painful (painful in regards that the family will get upset and you have a concept that says that it is bad if they are upset at you).
Only you have enough information to decide how best to approach the issue but if you want to be happy with yourself you will have to eventually.
Good luck and much strength to you.