How can I change things in my statement about a situation when I realize that what I thought was happening wasn't what happened?

my partner andni got into an argument that mostly was me working myself up to the point of hyperventilating myself and I thought my partner had reached for my neck when I realized later that he was reaching for my shoulders to keep me from falling backwards and hurting myself and the child I carry (I have a history of passing out due to anxiety and hyperventilating not due to my partner). I stated to the police that he grabbed me by the neck but he didn't and he shouldn't have to pay for the consequences of something that he didnt do and was actually just trying to protect me and our child. I thought what I was telling the police was true and honest and I dont wantnto sound like I was lying so I need advise on how to handle this