<sigh> the law also forbids drinking under the age of 21, supplying alcohol to minors, and driving faster than the speed limit. I'm sure I can find a whole list of laws that are broken all the time and willing to bet that you're guilty of some of them.
I feel sorry for anyone who has to deal with irrational parents like you. Imagine yourself on the other side of this situation. How would you feel if a parent threatened to have your daughter arrested, labeled a sex criminal for life, and beaten up by the mother and oldest daughter b/c she had consensual sex with a person she's in a relationship with?