Listen, if he's your partner and he's doing the stuff you don't want to do and you have paying customers, it seems to me it's worth trying to salvage over the next month. If your partner is doing more harm than good in certain aspects, why not agree that you need to formalise those aspects to accelerate growth, and then do it in a way that actually helps him not screw up?

For example: you say your website is a mess. If he can make it ugly, then he has too much control. Move to a CMS with a tight templating system and eliminate this pain point. If he's making repeat (and poor) feature requests, move to a formal feature request system with upvoting and make it public. Then you can point out that a particular feature has no user support. If you're answering the same questions over and over, institute an internal helpdesk system and just refer him to the answered, closed tickets and the search when he re-asks.

Basically, look at it as a management issue. The human factor is always going to be an issue no matter what startup you pursue; if you lack the soft skills to deal with it well, a systems approach might take you 80% of where you need to go until you've expanded enough to bring in another person who's designated job it is to take responsibility for these decisions.