My bf masturbated and he has a semen on his hand. he wiped it using wet wipes, we're not sure if he got it all since it's microscopic. after a few min. he fingers me, which means it's already exposed to air. can i get pregnant?

highly unlikely, sperm needs a fluid medium to migrate from the uterus up the fallopian tubes to the ovaries. A dry single solitary sperm to go from his fingers would be almost impossible

Pregnancy is not possible in above circumstances. Contraception remains otherwise key in avoiding undesired pregnancy and associated anxiety, specifically when intercourse becomes possible.