The answer depends in part on what your boyfriend's criminal background is like. If he has no record, (and this is assuming that he is only charged with misdemeanor assault and the related misdemeanors, rather than felony assault), then his sentence could be something in the range of 0-30 days in jail, 3 years probation, and some sort of anger management class. If he has a long criminal history, then his sentence could be significantly worse.
If he was convicted, a judge could order him to have no contact with the victim for the entirety of his probation - so potentially three years. However, if he does well on probation, completes his domestic violence / anger management classes, stays out of trouble, etc., and if the victim wants some contact, many judges may consider allowing contact before the end of probation.
He will likely go to court several times before his actual trial. If there is a trial, it will probably be in the next 2-4 months.
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