Forum games on ХВ are not the chillest thing; I too have sometimes gotten so heated I might as well have flown to Mars without a rocket. As for the current negativity, you're right that it's hard to handle. Probably the best thing is to try to convert it into inspiration—for example, you could write a furious post where a character curses everything and everyone. That way, the emotions subside a bit, and later you can reread it and enjoy it. Wiping—well, that's if you're absolutely sure you don't want to keep playing that specific character in the current situation, then sure. Though even then, it's better to discuss it with others beforehand rather than acting rashly, since we're all playing together.
As for suspicions, players' characters are always needed—it's not like Revan is going to play with himself. It can be hard to maintain a balance between RP relationships and metagaming, so ideally everyone should be friends to avoid having to force things later. Like with Nora—if Garrett had first met her on the ship without any personal grudges, who knows how to justify saving Mellen; you'd have had to get yourself out of that bind, and Garrett would just keep autistically clutching his skull.