Good luck.
In my case, a mass emailing was best. That way you can word things exactly right, explain, give background, tell how you feel, edit if needed, then send. No need to shock and confront anyone.
People will then have time to get used to the idea, and think it over before they see you in person.
When I came out to my immediate family (with a mass email) as a nonbinary partially transmale, there wasn't even a murmur from them.
Now they know, and there was no melodrama.