Can charges be filed against my half brother and I for having a consensual relationship?

Can charges be filed against my half brother and I for having a consensual relationship?
I’m an emancipated 17 y/o and he is 19. We live in Missouri. My mother, who I managed to escape the custody of, recently found out about the relationship. She lost him to his father when he was 5 because of a drug problem, so we didn’t grow up together, and when I met him, taboo as it is, it was love at first sight. Nonetheless, she is threatening to file charges against us if he doesn’t drop me off at a homeless shelter by tonight. I wanted to know if this was possible or if there is anywhere else I can go to avoid jail time or worse.

Justin’s Answer
The above attorney is correct, but I will add that Incest with a half-sibling is an E-felony in Missouri, punishable by up to 4 years in prison.