My son had consentual sex with a girl. Juvenile Court is involved due to police report made by her parents. How much trouble are we in for?

My 16 yr old son had consentual sex with a 15 yr old girl. We received a letter from Juvenile Court that a police report was made by her parents for rape. I’m stressing over this, we are in Missouri, how much trouble are we in for? We have text messages saved on my son’s cell phone and his friends cell phone about how she “wants to be with him” and how she is “proud she had sex with him”. Obviously we are saving these to take to the hearing. This happened over a month ago and we are just getting this, however, this girl is still sending him messages to his cell phone. Aside from the obvious fact this girl is trouble and he shouldn’t have anything else to do with her, I don’t want my son to go to Juvenile Detention.