1) May I know phrases / abjectives to describe Jane has been secretly falling in love with Brian but Brian does not know about it and only regards her as an ordinary friend. I know there is a word 'secret lover', but I want to make it more specific and touching in expression.
2) May I know some touching phrases / abjectives to describe how Jane was shocking and hurting after Brian texted her that he has just got married with someone.
In example #1 the situation you refer to is often called "unrequited love". But the sort of phrase you want is something like "secretly infatuated" or even just "infatuated" if the fact that Brian doesn't know about it is made clear in some other way. Another possibility is "crush": "Jane had a crush on Brian that was driving her crazy". However a crush is not always secret either and suggests something more superficial than love.
In many ways, simply saying "Jane was secretly in love with Brian" is quite a touching and effective way to phrase this.
In example #2 there are various possibilities.
"When Brian said he was married, Jane was devastated/shattered/broken-hearted etc". But strangely enough one of the best words for this is probably "crushed".
"Jane was secretly in love with Brian, so she was crushed when he told her of his marriage to someone else".
Perhaps others with greater experience in these matters can help you further.