Basically, after Phyllis blackmailed Angela, Michael asked them to both step down from the Party Planning Committee. Because there was too much drama. There was a problem with having one head of the Party Planning Committee. She becomes too powerful. So he appointed two heads.
What she means: Jim wrote Pam a Christmas card telling her how he felt in season 2 and was too afraid to give it to her then but kept it for 7 seasons and gave it to her in season 9 when he needed to prove to her how much she meant to him wow I’m actually not fine.
Dwight, listen: no matter what happens, you gotta forget about all the other stuff. You gotta forget about logic and fear and doubt. You just gotta do everything you can to get to the one woman who’s gonna make all this worth it. At the end of the day, you gotta jump. You love Angela, Dwight. I think you always have.