open (one's) heart (to someone)
To share one's deepest or most intimate emotions, thoughts, or secrets. Samantha finally opened her heart to me last night about how grief-stricken she's been since her father passed away. My father was a cold man, and he never opened his heart to anyone.
open one's heart to someone or something
1. Fig. to tell all of one's private thoughts to someone. I didn't mean to open my heart to you. She opened her heart to the wrong magazine, and it published a scandalous story.
2. Fig. to become loving and solicitous toward someone; to donate money generously to someone or some cause. We opened our hearts to Fred, who was soliciting for a good cause. We hope you will all open your hearts to our plea.