afraid to come out to best friend

How will i ever come out to my best of best friend ? We've known each other for like our whole lives, like almost ''literally'' i'd known him since when i was 4 years old, total 14 years. However i feel like we had this barrier thing between us, i wasn't really able to tell him anything. I even came out easily to my two other best friend of 7 years and 4 years easily, they seems to be more easy to come out to.

How long am i gonna be keep him in the dark? i've already started transition and it will come one day which he will ask questions, how am i suppose to answer them, i don't want things to be awkward between us. It feels like if i ever come out to him, my whole life would change, things would probably never be the same again.

Yes, i am a boy by birth. My best friends have still been treating my like a boy, i don't need them to treat me like a girl, i just want them to treat me as a normal human being, but not as a boy ! It's even weirder when i am talking to him about relationship, and how much i hope i would get a girlfriend soon, and yes i'm a lesb-trans. He would say like i was more handsome when i cut my hair, and i'd be like, no... but i was never able to tell him the reason.

We go a long way back... and he have totally no clue that i am a trans because i was never girly in anyway, probably because i see myself as a tomboyish girl ( trans ) + lesb ,  damm that's even confusing when i start to think about it, well we all know there's no fixed gender/expressions/etc
This could go on forever ~

Any FTMs out there have gone through something like that ? with your best friend.

-Juu
[Singapore]