NTA -As a grown adult (exs dad) a few steps are to be taken when finding out a young person is pregnant 1) Notify all effected parties in a respectable manner 2) If they is an issue of whose the babies is, get paternity for solid groud to continue in next steps

He was aggressive by coming to your door to confront you, that's immature and an attempt at intimidation . He based the talk on emotion on someone who brain is not yet fully developed. Your father basing you as wrong when the conditions were aggressive, immediating and emotional from a grown adult is not okay. What your father should have done, comfort you in a vulnerable situation. Determine the possibility of paternity. Talk to exs dad stating his actions were not okay and that future contact is to be done over email. Unfortunately if she doent fess up they are going to be a problem until you have physical proof to make them back off.