This sounds uncomfortable with your parent believing your sister. Do you sometimes say aggressive things and forget right away? Keep a diary to see if this situation happens again, or if it does, how often? Maybe your sister wants to criticize and feel powerful. That would be aggressive!

Don't pull away from people before you even know if there is a problem in how you speak. That is how a journal/diary can help you.

I am an American and we are different over here, but we may say several rude/aggressive things a week. That's wrong to do, but I try to start the next day being nicer with people. It's hard but keeps the mind healthy.

Like the American saying goes "if you fall off your horse, get back on it right away."