Into Lin's head #12.

I guess that's exactly it.

Your life has to go on regardless.

For anyone who's a strong empath,

it can be really difficult to carry on with life when your (closest) social circle is going through a difficult time.

Because of thoughts like, 

"I can't show my happiness to him/her because he/she is having a hard time"

or

"I must show that I am happy so that the things that upset me don't upset them".

But I think what we must all remember is that to a certain extent;
our lives have to go on.

Believe that there is balance
Share the emotions that you feel
Be happy for them when something good happens to them even if you're going through a rough time
Be there for them when the opposite happens.

I don't think the world is made just for
Sadness to be with sadness
and
Happiness to be with happiness.

I'm not saying it can never be that way,
I'm just saying that it's okay if it isn't.

The last thing your already-upset friend wants is to know that he/she upset you with what upset her.
Nobody (in the right mind) would want to drag another person down with them.

Don't worry.
Things don't have to be so complicated.
All you have to do is (appropriately) act the way you feel.