Leaving facebook depends also on your friends. If they understand your choice, then they will contact you with messages or phone calls. If they don't, then it might be more difficult.
What I'm thinging is that if I delete it, the ones that will contact me with an other way (messages, phone, email, ...) will be my true friends and not only fb friend.
Of course we will lost contact with John or Sara or Maria who is somewhere else in the world, but concretely what was the last we discuss each other ?
Facebook Messenger is a convenience that I have, but the people who do reach out to me usually do so just to organize a night out. They said they would call if they couldn't write.. We have group talks organizing board game nights, because communication is easier, and we have group chats for sharing random cute shit like cat videos. I do not get rid of it because for one specific friend I'd need to use Whatsapp anyway, because he is precious and I understand that he doesn't want Yet Another Secure Messaging App (telegram to be specific) on his phone/desktop just for me.
There's a difference between deleting and deactivating I think, I deleted mine.
That was it.
If you desperately need it, you will. When your out and about you wont have the pass as its in your draw at home