stew in (one's) own juice(s)
To remain alone with one's emotions, usually unpleasant ones like anger or disappointment. Kevin was in such a foul mood at dinner that I left early and just let him stew in his own juices.
stew in one's own juice
Fig. to be left alone to suffer one's anger or disappointment. John has such a terrible temper. When he got mad at us, we just let him go away and stew in his own juice. After John stewed in his own juice for a while, he decided to come back and apologize to us.