@jimortality As someone pretty much in your position (so I should probably shut up, but...well, it's me, so...) - as mentioned above several times now, what helps me is really just forcing myself to focus as much as possible on my own driving, my own lines and my own braking points, not on the guy in the mirrors. I just try to drive as much as possible like I would if he wasn't even there. If he wants to overtake, let him worry about that. The only thing I try to focus on is to not do any moves that would be considered unexpected (though I do not always succeed in that, especially when it comes to braking points).
And if someone gets at my side, well, at that point, my main priority is just stay on the road, followed closely by letting *him* stay on the road, meaning leaving him enough space.
And if someone seems very persistent trying to overtake to the point I don't feel good having him behind me or beside me or is clearly faster than me, I often just make it easier for him to overtake me as safely as possible. It's not that I literally let him go, but I deliberately take a slower line or something like that to give him more of a chance. I know this does not make for exciting racing, but I reckon I'd rather lose the position than worry for the rest of the race about if he'll make me miss my braking point and maybe lose more positions than one, or if we maybe take each other out fighting. Guess I'm not very good at that whole competing thing, I tend to be safe rather than sorry. This is also something public server racing taught me - in RD club racing, you can usually trust people to be able to keep their line and/or not ram you off the track, even if unintentionally. In public racing, it usually pays off to just be as far away from anyone else as possible
And quite often, if you let someone very eager to pass you go in public races, you'll see them go off the track just a few corners later, be it due to their own mistake or due to meeting someone who was just as determined in keeping his place as they were to pass him (and more often than not, they go out both).
Well, that's the theory at least. Probably not as ideal in practice (in fact I sometimes wonder if the person behind thinks I'm trying to block him when in fact I'm just struggling to stay on the road and blocking is the last thing on my mind
) and also might explain why I don't hold onto higher positions for very long. But I feel like I definitely panic a lot less trying to follow the above than I did a few weeks back, and I'm definitely not as frustrated when someone shows up in my mirrors breathing down my neck.