Wow, that does sound like an awful experience! It might mean law school isn't for you or not right now, but it might have just been a bad experience. I think everyone has felt like giving up at some point, especially when dealing with the stress of hanging onto waiting lists. I think you just need to think about why you applied in the first place. If it's because you are sick of your job and just want to do something, anything else, maybe it's best to wait and make sure it's what you want. But if you know you really want to be a lawyer, you should go for it. Maybe think about how you'd feel after withdrawing from your schools. Relieved or sad? That'll tell you how you really feel.
I would suggest waiting another year and retaking the LSAT. If you were doing that well on your practice tests, you would definitely do better next time. It would give you time to think about what you want, and you could get into a great school next year!