I agree that you need to surround yourself with positive friends...if you don't want to give up on the one you refer to...there are a few things you could try before you cut all ties.

Write down some boundaries that you would like to have with this person...whatever they may be and as they come up...assert yourself...

Example: You know I really enjoy being with you...it feels like though if I say the sky is blue you try correct me and it makes me feel pounced on. Please stop, so we can continue to enjoy each others company. When it happens again (and as I said before in other posts - it will), simply say you know we kind of already talked about this before...I'm sorry, but I'm going to need to end this call (head back home, ask you to leave, etc)

If you don't feel like spending the energy on this person don't...maybe it will come in handy with someone else...