I fell inlove with my best friend

I fell Inlove with my best friend. She's so nice and sweet and I love her soo much. Texting her makes my heart flutter and I'm filled with joy. But she has a girlfriend, and I don't know if I should tell her or anything. She means the world to me and I want her to be happy, but I can't stand the thought of her with that bitch.

I need help