You can't help what you feel, you can only control how you act. So, other than getting used to seeing and being around them, you can't really do anything about it.
As for the game...your only hope would be if you were on PC and someone made a mod for the game to remove spiders and spider like creatures, because honestly, with your fear, the rest of the game will likely be torture. Wookie planet is the worst, but there are spider or spider like creatures on just about all planets.
Sorry, you are hating this, and have this issue, and I wish you the best in dealing with it, but I don't think you will be able to finish the game yourself, until you can deal with 8 legs better.
I personally hate spiders crawling on me when I don't expect it, and don't really like it when I do expect it, but I can deal....I also respect the place they have in the environment, killing all the OTHER creepy crawlies and flyers that I hate more...
