I want to know what this line mean in hamlet:

but break my heart for i must hold my tongue

why do Hamlet not want to share his feelings with anyone?

3 answers

http://nfs.sparknotes.com/hamlet/page_28.html

Hamlet doesn't feel he can say what he thinks because his mother has already married this man. Hamlet loves his mother too much to hurt her feelings, plus His mother and uncle have already told him to stop being so extremely mournful for his father. They don't want to hear anything more from him about why he feels so awful (why his heart is breaking).
thanks very much Writeacher :)
You're welcome, Mohammad!