I'm sorry but please help me

Hello? I wanna talk abt this since i was so confused and I'm sorry my english is bad

My friend's sister suddenly became a part of LGBT. She was straight before and then someone came saying that she love her. At first her sister was like "no, i'm straight but it's fine if we're just friend". Time passed by and suddenly she declared that they became a couple. She declared it everywhere but not to her family.

My friend found out abt it accidentally, she got shock and crying so badly that day. She really confused and me too
We're from Muslim family and LGBT is prohibited in our country. My friend even thought abt telling her parents but it's gonna be a bomb for her familly. She is the one who know abt this in her family. She even thought to make a distance with her sister. At least she want her sister tell her

But my friend still confuse, don't know what to do and me too
I hope you all give a kind suggestion

Thank you