She's clearly crossing the line by initiating the conversation with you.
You have already showed no interest in meeting her by refusing to go to the
party, now she's manipulating you to make you change your mind.
She probably did the same to your dear Jacob by convincing him that he
should have brought you to the party.
If I were you, I would just ignore her. And your Jacob should respect your
wish if he cares about you.
If he gets upset about this, then he's not your man. There is only room for
two in a relationship, not three. An break up will save your time.