If you do not attend court once you have been told you have to , the court can have you arrested and taken to court.
If you refuse to speak at court, the court may decide to treat you as a 'hostile witness' this means that they think you are so scared of your boyfriend that you dare not speak.
You need to attend court and tell the whole truth.
Remember you will be 'on oath' to tell
' The truth, The whole truth and nothing but the truth'.
Not telling the truth under oath is a very serious offence , it is called contempt of court which can carry a prison sentence.
I am baffled by your solicitors advice to say you do not remember, which is actually telling you to lie under oath.
( unless of course your solicitor knows more than we have been told here?)