Tell ur sis how you feel. Even if she doesn’t like him she still needs to be supportive. And if that doesn’t work try and find a new guys! He might not be the one. But if your sister does end up likening him be supportive.. then Tom can see that your still a great person inside 🙂
i know it may hurt but you cannot force him to like you the way he likes her. I would try to maintain the friendship. Who knows? Maybe your sister doesnt feel the same and he will see how supportive you are and love may form.