I've only watched the clips of this reunion but Shamea is really embarrassing. She really fumbled all the goodwill she had in the first few episodes
Also, I agree with that tweet saying she clearly has a problem talking about things that hurt her in regards to her friendship with Porsha.
Like, she never really got over it or expressed how those things made her feel, so she's held on to it and it's made her resentful a bit.
She's like that friend that's secretly mad about something you've done years ago but never tells you and just starts acting weird.