disclose sth or ... sth

wear your heart on your ....

express your feelings  = .... sth out

careful not to give too much information away (cautious or ...)

stop yourself from showing your feelings (.... your feelings)

held back or ... -up

private or ... thoughts 

weak 

I didn't have the ... to tell her bad news (phrase).

feel uncomfortable to tell sth (synonym for the word in italics)

stop yourself from showing negative emotions (.... up your emotions)

tell people secret information (... sth away)

She tool part in the dancing competition but you could tell her ... wasn't really in it.

My heart told me to help him. = Emotionally, I felt I should help him.

Pent - up ... can lead to anxiety and depression.