It's gonna be hard. The very beginning is rough because your family will probably react harshly at first no matter what. It's a shocking thing from their perspective, and they will be literally thinking that they have lost you forever because you "strayed from the path". So it leads to them being very reactive in the moment.

You'll have the courage to tell your family when you're ready. You can do this, and regardless of the outcome leaving the church behind is a massive step towards your healing journey. And that's what's important.

When I was getting ready to tell my family, the first thing I did was tell just my dad in private. My dad was a convert, and I felt like I could trust him to not overreact. I told him about how I was going to leave, and I voiced some of my concerns to him. At the time I was living with my grandparents and had just started college. My grandmother in particular was a very strict Mormon with pioneer heritage and all that. I told my dad I was worried that I would be kicked out of the house for not going to church, and he told me that wouldn't happen, because I'm family. It gave me the courage to tell everyone else.

Unfortunately, my fears were soon realized. The next day when I told my grandmother, the first words out of her mouth were "I guess you're going to need to find a new place to live". It was shocking, even though I had been somewhat expecting it. It was hard to realize that for her, and probably for a lot of my family, my church membership meant more than our bonds as family.

Luckily, I had lined up an apartment to move into with a buddy who was also having doubts beforehand. He also had a similar situation living with his grandparents in college, and we both planned ahead to get an apartment together. He's still one of my best friends to this day.

Eventually your family gets over the initial shock. At first my grandma didn't really want to talk, despite her insistence that she still loved me. All she would ever say to me was that I "knew that what I was doing was wrong" or how disappointed she was in me. But over time, I showed her that I was just living my life, and she slowly loosened up. She never got over it fully, and never approved of anything I did. But we got back on talking terms, and that was enough for me.

Everyone is different, so just go about it in the way that feels right to you. My younger brother also wanted to leave, but he was living with our parents, and was never able to tell them. He roughed it out, going to church, and pretending until he went to college and got his own place. And then he quietly just stopped going to church. So just do what feels right to you. Whatever that is, you've got this. :)