I think that the better option would have been to be kicked out rather than leaving voluntarily although neither option is good for you.  By failing to fulfill the conditions of probation and complete the program you have technically violated probation.  That could result in your probation being revoked and you being sentenced to the crime as originally charged and with the original penalties.  I would go and speak with your attorney on this matter as soon as you possibly can.  Maybe there is a way for him or her to run interference for you here given that completion of the program was so close.  Do not wait until you have a warrant issued for you.