It's like choosing between bf and parents

So it's kind of a long story but I need advice. My boyfriend and I have been dating for two and a half years here soon and we've been sexually active for 1. I have kept this very very quiet because my family has strict rules against it. I personally do not care whether or not it is wrong in their faith. I do not share the same feelings. My boyfriend and I have decided to finally move in together and this needless to say brought out all the things I've been hiding. I have never felt so broken in my life to be so loved by three people and torn apart by the choices my parents are having me make. I felt like I had shot someone with how they are reacting.

So here's my question: I want to be with my boyfriend. We're planning on getting married this summer. This does not appease my parents. How do I keep my relationship with my parents and still make my own decisions as an adult without feeling as if I've stabbed someone in the back?