Am I over reacting

My boyfriend got in a car accident and didn’t tell me until the next morning . when I went to make sure he was ok his sister would not give me a chance to speak to him alone she sat in front of me while we were speaking about what happen He said nothing . She also walked with me and him to my car after I spent a few hours there . She’s 31 . And just wouldn’t give us space idek what to do anymore. Advice ?