What does it mean if someone says you really are a heel?

If someone calls you a "heel," they are implying that you are behaving in a dishonorable, unscrupulous, or untrustworthy manner. The term originated in professional Wrestling, where a "heel" is a villainous character who cheats and acts against the interests of the audience or other characters. In everyday conversation, it's typically used to criticize someone for being mean or deceitful. Essentially, it's a way of saying that you've acted poorly or hurt others.