Should I act like nothing bothers but secretly I'm depressed because I'm in love with my best friend?
That does not sound right. Why are you depressed about being in love?
I've been crushing on my best friend for 3 months already, if she finds out I would feel so embarrassed.
It is hard to admit your feelings sometimes but when you care about somebody you should tell them. It will help your relationship move forward.
She just texted me and said she's in love with me. WTF, I can't believe it.
Well I am glad that she seems to have feelings for you too, but next time you should share your feelings with her. Then you wouldn't have had to suffer for 3 months.