Why did my friend get mad I didn't tell her I was Bi?? Whats so important about it?

Okay so I was telling a group of friends how my trip had went and I told them how I got with this one hot girl I knew from my past. My friend tripped out. She accused me of being fake and not a real friend. Called me a, this is a quote from her "miff diving lie-ing dike ***** who can't be trusted" then she stormed out I never told her I was bi and when i met her I had a bf. I don't think its that big of a deal that I'm Bi and as much as i like women I know I am going to marry a man. What's her deal its none of her business anyways its not like I'm hittin on her or something shesh. Am I required to tell everyone im bi or something??!!!