A Florida man has been arrested after he shot and killed his girlfriend while she slept in bed with their three children, deputies say. The man then allegedly attempted to stage the murder as a home invasion. Authorities say Saun Rainge and his accomplice, Benjamin Garmon, now both face a first-degree murder charge for the death of 30-year-old Porshe Nikita Shanee’ Streeter. None of the children — ages 10, 2 and 1 — were injured in the shooting, officials said…