Criminal Law Questions? Ask a Criminal Lawyer.
As the primary resident holder you are responsible for knowing who is in your home and what their behaviors are.
Now, you can go to court and explain that you did not invite anyone under the age of 21 to your party. But the court is going to hold you accountable.
As to the police entering, they may do so if they have reason to believe that criminal activity is occurring.
I suppose you will be charged with supplying alcohol to minors, possession of marijuana
It may be best to consult with a local attorney to have those charges dropped, if possible
They are both misdemeanor crimes and do provide for a jail penalty. A first offender would get probation and possibly a deferred adjudication. So you would be fined and court costs, community service, etc