How to testify on my boyfriends behalf to help my boyfriend?

How to testify on my boyfriends behalf to help my boyfriend?
I’ve been subpoenaed to court to testify as a witness for St of Missouri against my boyfriend for charges I didn’t want to press when I was asked. He didn’t hit me. I was under medication during time of incident and may have exaggerated to the scene and added to it because I was mad

Justin’s Answer
You do not get to decide what testimony to give. The attorneys or defendant will ask you questions, and you must answer honestly under penalty of perjury.