A couple of things:
1) Picking a co-founder should be treated as seriously as picking your wife or husband. So the best way to avoid conflicts is to really date as long as possible.
2) 50/50 splits almost *never* work between co-founders. Unless you are already very close friends with a lot of arguments and challenging scenarios behind you, I think co-founder scenarios that are most healthy are where there is a decisive difference in equity (in excess of 60% to the one Founder).
3) 4-year vesting & shareholder agreements ensure that if a Founder leaves or is fired, the remaining unvested shares are cancelled.

The idea of a class of shares specific only to you is a *really* bad idea. It makes you appear unfavorably to others (especially potential investors) and absent massive traction, a deal-breaker for anyone but incredibly unsophisticated investors.

I would also be remiss if I didn't answer your question by asking you to reflect deeply on your own involvement as a leader and whether the differences of opinion could and will be handled differently with other employees and co-founders. The best founders I know encourage differing points of view and are willing to change their own opinions when presented with stronger options than their own.

Obviously, I don't know you so or the individual(s) you were involved in but ultimately, every move a startup makes is the Founder's responsibility.

Happy to talk in a call if you have any questions.