1-i agree with you that she deserves to be insulted, what kind of piece of shit tries to get pregnant from two different guys? she is forcing a baby into a bad situation
2-insulting her did not help you in this situation, it didnt accomplish anything and will make it harder to get her to agree to a paternity test.
3-i wouldve pretended to be super supportive and start by saying that "I want to be involved in the pregnancy, birth and childhood of my children", that way i could go to doctors appointments and then make the paternity test nonthreatening
because either
a-its not your kid, and you can find out right away and put this behind you
b- it is your kid, and you can find out now, that way there isnt this battle and tension in the air