If you choose the former, it should start with a frank but non-confrontational conversation among all of you where you discuss what is and isn't working with your relationship. Don't overfocus on the business. The day-to-day of a startup grows from the relationship among the co-founders. That's always at the root.
For example, if the business model isn't working, why don't you have a relationship where you can say "Guys, this business model isn't working. We have to do something different. Let's figure this out."? Over-focusing on the business will result in a laundry-list conversation when everyone just unloads their grievances all at once. It's not productive.
If going into the conversation you feel the urge to let your co-founders "have a piece of your mind" then don't have the conversation. You need to be calm, in control, and aware of the real source of your own frustrations.
Most likely there's a long series of missed-but-unstated expectations, both big and small. You have to acknowledge your own responsibility in this situation, viz., as a co-founder you have a responsibility to bring these up the second they happen to avoid a "blow up" situation. Yet here you are, in just such a situation. You're partially responsible for that, whether your co-founders are actually idiots or not.
You have to be prepared for your co-founders to feel similarly about you. Avoid the trap of allowing the conversation to become a tit for tat. "You forgot to publish that blog post." "Yeah, well, you forgot to follow up with a potential investor!" etc.
It might help to reframe this conversation from one where you're going to tell them all the things that aren't working to one where you ask for help with the things you think aren't working. If you don't want your co-founders to be defensive then you need to be vulnerable -- probably much more vulnerable than you're comfortable being.
Good luck. Welcome to startups.