NO you don't have to take a BEATING. Disparity of force would come into play, which basicly is one individual being unable to provide the same amount of force as the opponent due to physical difference,defect or age.
However you will have to articulate to the "reasonable Man" standard why you felt the need tor the use of deadly force. Someone slapping you in the face or giving you a shove isn't going to do it.
Florida 776.012 Use of force in defense of person.—A person is justified in using force, except deadly force, against another when and to the extent that the person reasonably believes that such conduct is necessary to defend himself or herself or another against the other’s imminent use of unlawful force. However, a person is justified in the use of deadly force and does not have a duty to retreat if:
(1) He or she reasonably believes that such force is necessary to prevent imminent death or great bodily harm to himself or herself or another or to prevent the imminent commission of a forcible felony; or
(2) Under those circumstances permitted pursuant to s. 776.013.