This is why options are good, and having a firearm as the only one is not.
A situation such as this is custom designed for a little a$#hole repellant, AKA OC or mace. Clearly state your intention to leave the situation, take a step back to begin your departure and if the BG doesn't quit, paint the fence.
If lethal means are the only tool you have other than your fists and feet, you're in a pickle. In Ohio, the legal standard is not just AOJ, but the BG must also have comitted an overt act that establishes his intention to visit GBI or death on you, and verbal threats alone do not meet that standard.
The responses for you don't change much, clearly state your intention to disengage and leave, begin making moves to initiate your retreat, and if the BG continues to press forward, you have an additional articulable fact aiding your case for justification if you have to act. The problem remains that he has just as much right to the public street that you do, and until he commits that overt act that places you in immediate jeopardy of GBI or death, your hands are tied from a lethal force perspective.
Once fists start flying, the game is changed. If you're advancing in age, and you have cardiac conditions, high blood pressure, arthritis, etc that limit your ability to engage him physically you may be in a position to shoot that I, as a reasonably fit man in my 30's who can still get 275 off the bench, will not be in. I'm going to have to scrap for a while, or paint the fence.