No one can answer your question with the very limited facts you have provided. Fraud is never a good idea and if the fraud was committed to induce the employer to pay you severance then the answer to your question is probably yes.
Not legal advice / No lawyer/client relationship.
The fraudulent acts you may have committed would not necessarily preclude you from receiving your benefits if the acts did not cause the employer to pay them. As they appear to be unrelated to your job, my initial reaction is that they would not be a basis for stopping the benefits.
If you had committed fraudulent acts against the employer or business, it may be necessary for the employer to have you charged and convicted of the fraud in order to receive restitution which can be recovered as an offset from your award.
Both the Agreement would need to reviewed and the alleged fraud examined. Contact an attorney to provide these details and I am sure your questions can be answered.