People who have a burning fire of anger and hatred inside them against others but cannot express those feelings openly due to their cowardice may be described as "resentful," "bitter," "vindictive," or "envious." It's important to note that labeling individuals solely based on their negative emotions can be reductive, and complex human emotions can be driven by a variety of factors and experiences.
It's essential to approach such individuals with empathy and understanding, as their internal struggles may be indicative of deeper issues that need addressing. Encouraging open communication and providing support can help them navigate their emotions in a healthier way. If someone is experiencing significant emotional distress or posing a threat to themselves or others, it's crucial to suggest seeking professional help or guidance from a mental health expert.