pour out (one's) heart (to someone)
To share one's deepest or most intimate emotions, thoughts, or secrets, especially in a profuse or sudden manner. Samantha poured out her heart to me last night about how grief-stricken she's been since her father passed away. Sorry for pouring out my heart like that. I've been keeping those feelings bottled up for a long time.
pour out one's heart
Express one's innermost thoughts and feelings to someone else, as in Upset over the breakup, she poured out her heart to her mother. Also see open one's heart.