If you refuse to answer as directed by Council, you may be held in contempt of court, which can result in a fine, or if the juidge decides it is serious enough (very unlikely in this scenario) there can be a a custodial sentence.
From the tone of your messsage - "he ONLY assaulted me by grabbing me ..." it appears that maybe you are having second thoughts?
This sort of approach is at the root of the epidemic of domestic violence in this country.
Because you feel he may be punished as a rsult of your evidenvce, you feel reluctant to spek.
Wrong - he will be punished because of his actions - assault - not yours - telling the truth about it.
If you backtrack now, what happens? Do you have to wait until he 'only' blacks your eyes or breaks your arms?
This man is violent, and he must be stopped. You feeling guilt or a misplaced sense of 'mercy' will not stop him - it will simply grant him the freedom to excuse himself from doing it again - and believe me, he will. He has a suspended sentence - I assume this is also for assault - so the message is not getting through to him is it?
Go to court, speak your truth, and hold your head up high.
You do not have to suffer physical abuse from anyone, that is why the law protects you.
Do not weaken on the day - he won;t weaken when he assaults you again - and next time he won;t stop at 'only' grabbing you.
Good luck.