Hi! My name is XXXXX XXXXX I'll be the attorney assisting you.
Yes, your lawyer is correct - the ADA needs your wife to testify to the events and you have the constitutional right to cross-examine witnesses against you.
If she doesn't show up or appear at trial
- the judge has two options: 1) dismiss the case, or 2) postpone the case.
Usually the judge will dismiss a domestic dispute case rather than postpone the case because they realize that the spouse does not want to pursue the matter AND/OR
will change their story as to the events (their memory becoming vague about matters or that they started the event or that it was accidental how they were injured).
Generally medical records won't support a conviction by themself in most matters - especially in an assault and battery case because of the burden of proofs (the elements of assault and battery) that the ADA must prove.
So, if your wife doesn't show or refuses to testify or changes her testimony about the eventsd - the ADA will have no alternative but to nolle pros the case or the judge will dismiss it.