I believe that the first thing you have to realize is - that in this startup - you are a) not the founder, b) not the team lead -- and you are not responsible for fixing the issues of this startup on those levels -- they are.
The first thing you need to drop is the (perhaps mainly subconscious) _pride_ for (almost single-handedly?) carrying this startup to (almost full?) execution, which is what self-puts you on the cross of suffering. No, you are not owned by the code you created. You are free, you did your best, it will be on your resume, and you owe nothing to anybody.
Take your vacation, advertise your impending demise and/or ask for a raise, think about your own startups. Be friends with the team lead from within the confines and limits of your role. If he wants you to do something, try to do it to the best of your ability, but be conscious to not overwork and not worry about things others are paid to worry about. You don't know if the problems you currently face are fully solvable, maybe they aren't, and that's not your cross to carry, so simply don't carry it.
He said that he believes the founders aren't aware of the team lead creating problems for him.
At the moment it's simply unknown which of the two they value most, the OP, or the team lead.
The most reasonable course of action isn't to focus on humility right now, it's to figure out which approach the founders value most, the OP's, or the team lead's.
There is no reason for false humility, in fact selling himself on his technical record is the best card he has to play.
Usually people higher up in the hierarchy are by definition valued more than grunt-level workers. So OP should assume she is at the bottom of the ladder and importance. Founders could be good friends with the team lead and completely biased towards her opinion.
I would recommend against assuming anything. It's a start up not IBM, things are more fluid.
I've used this strategy before in real life, more than once and it resolved the issue 50% of the time.
If it doesn't resolve the issue for the OP, all he does is quit. He was going to anyway.
You can't be afraid to tackle these issues head on. There's no need to be afraid to talk to people.
Do you think the founders just ignored the VCs and didn't negotiate with them for the best deal they could get? That they don't negotiate with their customers?
The first thing you need to drop is the (perhaps mainly subconscious) _pride_ for (almost single-handedly?) carrying this startup to (almost full?) execution, which is what self-puts you on the cross of suffering. No, you are not owned by the code you created. You are free, you did your best, it will be on your resume, and you owe nothing to anybody.
Take your vacation, advertise your impending demise and/or ask for a raise, think about your own startups. Be friends with the team lead from within the confines and limits of your role. If he wants you to do something, try to do it to the best of your ability, but be conscious to not overwork and not worry about things others are paid to worry about. You don't know if the problems you currently face are fully solvable, maybe they aren't, and that's not your cross to carry, so simply don't carry it.