The degree of torment the demons are permitted to exert does not decrease as you increase in sanctity. If you are sometimes shocked at the wickedness, its depth or its stealth or its cunning, that is actually a good sign, provided you deal with it the right way. If you fail, go to Confession, and then keep memory of the incident top of mind, to inform your bearing.
Temptation itself is not a sin. It is literally the way by which God works perfection in us. In resisting temptation, patiently enduring tribulation, we merit additional graces, and continue further down the road. Every defeated temptation is a victory. Start making a record of them. You will need many such.
“And now, brethren, as you are the ancients among the people of God, and their very soul resteth upon you: comfort their hearts by your speech, that they may be mindful how our fathers were tempted that they might be proved, whether they worshipped their God truly. They must remember how our father Abraham was tempted, and being proved by many tribulations, was made the friend of God. So Isaac, so Jacob, so Moses, and all that have pleased God, passed through many tribulations, remaining faithful.”
-Judith 8:21-23, (entire book removed by Luther and cannot be found in Protestant bibles to this day)