Hey there. Enjoy your stay in this forum. Everyone's relatively normal, but we do have a few whack jobs popping up now and again, bashing their bibles and Qur'ans around the place!
Also, your situation is very similar to what mine was, and many others I'm sure. If you want to be honest in any sense of the word, you should definitely come out. The longer you wait, the worse the situation will get. What if you married your girlfriend, and then came out after so long? That would not end well I can tell you. If she dumps you because to your beliefs then, quite frankly, she doesn't deserve you. You would be far too virtuous for the her. As for your parents, remember this: if the nature of your relationship changes when you come out, the split will be entirely their fault. You need not worry though, most parents, mine included, are considerate enough to love you despite your opposing beliefs. Coming out will free you up massively, and an enormous weight will lift. I think the hardest part of this will be finding a point in a conversation where you can tell them your choice. Good luck bro!
Also, your situation is very similar to what mine was, and many others I'm sure. If you want to be honest in any sense of the word, you should definitely come out. The longer you wait, the worse the situation will get. What if you married your girlfriend, and then came out after so long? That would not end well I can tell you. If she dumps you because to your beliefs then, quite frankly, she doesn't deserve you. You would be far too virtuous for the her. As for your parents, remember this: if the nature of your relationship changes when you come out, the split will be entirely their fault. You need not worry though, most parents, mine included, are considerate enough to love you despite your opposing beliefs. Coming out will free you up massively, and an enormous weight will lift. I think the hardest part of this will be finding a point in a conversation where you can tell them your choice. Good luck bro!