Even if you know your anger isn't logical or justified, you can't always help how you feel. Emotions aren't always rational and logical. Feelings are neither right or wrong, good or bad. They just are. And for some of us, being angry may be preferable to feeling the underlying hurt and pain of loss.
Anger is a powerful emotion that can be frightening.
But feeling angry doesn't necessarily imply that you will lose control or take your anger out unfairly on others. Before you can get through it, let go of the intense emotions attached to it and move on, your anger must be admitted, felt and expressed, if only to yourself. When you simply acknowledge feelings of anger to yourself or to a trusted other without actually doing anything about them, no harm is done, to you or to anyone else. On the other hand, if anger is suppressed and held on to, eventually you may erupt like a volcano, internalize it and get depressed, or misdirect it toward innocent others. Think of anger as a sort of heat-seeking missile.