Also was in a similar situation about 25 yrs ago in Pgh, PA.
Intervened in an assault, turned out to be an attempted kidnapping, by a feral yout on a little blonde college girl. Jumped in, unarmed, without adequately surveying the situation.
Instead of 1 perp there were six and I ended up with the back of my head split open with a brick and the perps trying to stomp and pound my brains into the pavement.
Saved the girl though, started carrying the next day and haven't stopped.
Regardless of what you think now, you did the right thing. You intervened and that girl was saved. God bless you and we need more like you.