Feelings are not sinful if you can’t control them. Let me get back to that, though.
Our morality is not based on utilitarianism, but on virtue ethics (under the Teachings of Christ and Church, etc). One should be virtuous. Not merely not do evil, but not want to do evil. I.e., the man who wants to kill the king but cannot is also evil and guilty of murder in this sense, as is the one who wants to kill the king and succeeds.
Sins are those things that offend God.
Feelings should be arrived at rationally. We are rational beings after all. So, anger is fine, if it makes sense to be angry. I.e., righteous anger, and for example Jesus whipping those selling things in His Father’s House.
We are told to be like children.
Note that we can’t all control all the thoughts that pop unto our mind, or feelings too. It is if we WILLINGLY allow sinful thoughts etc to happen that it is sinful.