Me (20M) Her (19F). My girlfriend became extremely religious out of nowhere. What to do?

We’ve been together for two years and a half. Since I met her, I have known she is Christian but she was not fully devoted, and Religion is not that important for me. Everything was going great but recently she has become extremely religious. She has said that now she wants to devote her life to God and she wants me to do so as well. We’ve had sex before and now she wants to wait until marriage (when i met her, she said she wanted to wait until marriage to have sex but we still ended up having sex and we both enjoyed it, and we’ve done it for more than a year without any issues). Now she’s telling me that having sex was a mistake and that’s not what she really wanted. I don’t know how to feel, I don’t feel like I even know her anymore. She was great, I love her to death and I’m aware that women like her are hard to find. We always respected each other, shared similar hobbies and time together was amazing. I feel so attached to her but I’m heartbroken, everything changed so quickly. I assume that no sex before marriage is not the only thing that is going to change, and I feel that in a future we are going to go by her terms, and what is right for her and her believes, even if those believes are against mine.