My advice? Get new fucking friends! They sound shitty enough to be gossiping behind your back about you.
I had a friend who hated being pigeonholed into gay/bi/straight. She suddenly fell for a woman one day... so fucking what? It's the person she fell for, not the gender.
People who care about you will be more concerned about helping you through the confusion and making sense of your feelings, if that's what you want. They should not be more concerned with telling that juicy bit of gossip to your mutual friends.
The fact is, relationships and love don't come down to gender. If you fall for someone it's more than likely due to their personality and you don't have to put a name on that yet. You dont have to fall into a category just because it makes life easier for your mates to process.
They should be supporting you.
I'm sorry they've reacted this way and you need to make it clear to them it is not okay, in any way, to have done that. You should be able to trust them and you can't anymore.
Like I said above though, until you process your feelings, you DO NOT have to put a label on it. Take time, be happy, it will come to you. Find someone else who won't see your situation as a source of entertainment. Life is much happier when you find friends who love you just as you are 😊