The start of the scene shows her in agony over something or someone. The person is practically given away when she mentions "My mistress with a monster is in love." This is sentence indicate that she is talking to herself about her friend betrayed her over a man. The standout sentence is "And forth my mimic comes. When they him spy", it's saying that after the spell casting of his head turning into a donkey. The mimic or the presence of the magic in form of donkey comes when his friends are looking for him, that's what they find to their surprise.