Unfortunately, your priest is lacking in this area of Church teaching.
Baptism does, indeed, wash away Original sin. The EFFECTS of Original sin remain, however. These effects are darkness of intellect and weakness of will. God, though, in His infinite love and mercy, makes it possible to get right with Him after we sin. The angels who fell, cannot be made right with God, because they have no excuse like we do (darkness of intellect/weakness of will). They have what’s called instant discernment. They decide in an instant whether to follow God or not. Once they decide, they cannot change their minds. They can’t say, “Oh, wait. I made a mistake because I’m afflicted with darkness of intellect or weakness of will.” They’re “stuck.” We, on the other hand, can say that. And, we CAN, with God’s grace, repent and confess our sins and be made right again with God.