I don't think your friend is retaliating against you. I think your friend is attempting to dig out of her 100 foot hole with a toothpick. Smoke and Mirrors.......wants to keep the BF. You make "allegations", her Ex is pissed, her bf is pissed, and she has got to cover it ALL up. Calls the cops on you. Clever, yet ineffective. If she wasn't such a mental case she might have given pause to making the call that is sinking the ship.
Anywho.....when we deal with toxic people well (LOL), we collect them. Good time to clean house.