I have over 4,000 hours coaching business owners and 10 years facilitating peer groups. I have 3 coaching certifications and I've organized and curated 3 TEDx Conferences. The third most viewed TED talk of all time, Simon Sinek's "Start with Why" talk, came from my first conference.
I started out as a CPA for Ernst and Young, got my MBA from University of Chicago, worked as a strategic planning consultant and ran P&Ls in Fortune 500 companies - all before I started coaching business owners.
I've run 10 marathons, climbed Mt. Rainier with world-famous mountaineer, Ed Viesturs when I turned 50, did a half ironman at 51, did Tough Mudder at 52, got my 200 hr RYT yoga cert at 53, and I turned 54 this year and I'm doing Karate. (And yes, my photo is current.)
Your company is only as healthy as your partnership. Time spent working on your partnership is an investment in your company. That said, check out David Gage's book, The Partnership Charter. http://www.amazon.com/The-Partnership-Charter-Start-Business/dp/0738208981 It outlines a process for threading your partnership back together. (It's brilliant and one I've used several times)
BTW, paranoid is a fairly common personality type. It is how some people view the world. (Don't take it personally.) Andy Grove, the former CEO of Intel, is a famous paranoid and it has served him and Intel well.
Whether or not you should bail depends upon how passionate you are about the business and how willing you are to work on both yourself and the relationship. If you love the biz and are willing to do the work, investigate your partners willingness to do the same and get the book. Good luck.