Fingering doesn't transmit HIV and neither does trivial penile contact with vaginal secretions of the sort you describe. And the chance your partner had HIV is almost zero. 1,2) You aren't at risk and do not need testing. 3) In theory a cut on the finger might increase the chance, but increasing a virtually zero risk still leaves virtually zero risk.
No "yes but" or "what if" questions, please. There is nothing you can add that would change my opinion or advice. Best wishes.
HHH, MD