open one's heart to
Confide in, reveal one's thoughts and feelings to, as in Last night Meg opened her heart to her sister concerning her marriage. This expression uses heart in the sense of “the seat of thought and emotion,” a usage dating from the 9th century.
The American Heritage® Idioms Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.