open up

open up (to sb) (about sth) (show one’s feelings, express oneself) — открыться, признаться (в своих чувствах)

Example 1: He loved her so much that he was finally able to open up about his deepest feelings. (englishbaby.com)

Example 2: Oh, please. Come on. I know it’s probably hard for you to open up about your feelings, and it’s probably even harder for you to open up to Greta about your feelings, but you need to let her know how you feel. (englishbaby.com)

see also
[come clean]
[get sth off one's chest]
[make a clear breast of it]
[out of one's system]