FEELINGS FOR BEST FRIEND?

How do I tell if I have feelings for my best friend. Like I’m pretty certain I do and I know she does too. I’m nervous about ruining our friendship! Also I’m not really into sex that much so I’m worried that will affect things. Is it something you only know after giving it a shot? I’d be pretty chill about remaining friend after a relationship but wouldn’t know about her. Also if I’m not very sexual what makes it different from our close friendship?