Or at least, these things are hard to discern because of our own lack of holiness. There’s a wonderful book, “Self-Abandonment to Divine Providence,” where Fr. J.P. de Caussade explains that God often hides the gifts we have from us, because we are in danger of becoming proud, even though He is in fact working good things through us.
“We compel God to conceal his gifts from us and the interior riches with which he adorns us. Otherwise, the smallest breath of vanity or complacency, however imperceptible, would rot and destroy these flowers and fruits. Once you are in a state to wear and enjoy these without danger, God will cause your eyes to open. Your only endeavor, then, will be to praise and bless him, forgetting yourself and rendering all the glory of your deliverance to your divine Liberator. Meantime, follow the present guidance of his Holy Spirit, and do not terrify your heart. Be sure that there is no sin in all you are experiencing at this time, since you endure it with so much grief and you would know such happiness could you extirpate these wretched results of your sensitiveness. Uphold yourself in this blessed longing; offer up your prayers; be patient in your petitions; above all humble yourself before God: he it is who will complete the work he has begun in you; there is none other able to perform it. Recognize that this is the delicate sacrifice God asks of you before filling your heart with the ineffable delight of his pure love.”
Your feelings of anger are not sinful. When we choose to do good to our enemies, despite our anger, then we are loving them and loving God through them. But of course we need to pray for this. You may feel powerless in this trial, but by trusting less in yourself, you have much greater cause to trust completely in God, who alone will lead you in holiness.
Hope some of this is helpful.
Ave Maria and God bless!