The amount of damage you caused will drive the sentencing. This could be criminal tresspass and misdemeanor criminal property damage all the way up to felony property damage. There simply is no way to know how much all the damage you did will cost to repair.
Hire a lawyer TODAY and make a plan.
Misdemeanors carry a stiff fine and jail time up to one year. Felony convictions are longer.
The advice, above, from Mr. Brinkmeier is in all respects correct. But I wanted to add a small general observation. When talking about an unresolved criminal or potentially criminal matter, it is unwise to gratuitously state that you committed a particular violation of criminal law. It is far better to state that you are accused or suspected of the particular crime. If your boyfriend (or ex-boyfriend, as the case may be) reads your question, and a criminal proceeding is ultimately brought, you could find yourself in a tougher position by virtue of the admission that is inherent in your question. In such a case, if you can be linked to the question, your chances of being found guilty are increased.
Good luck to you.