This makes no sense to me, how can a 1 coulomb point charge exert the same force as a 1 trillion coulomb point charge. I know Newton's third law, but I still can't comprehend this.
I think the issue here is partly your intuition of force.
The force exerted, as the formula shows, is the result of the product of the two charges involved. It is an interaction of two things, not a force produced by one.
The deep reason for this "product rule" is explained by Quantum Electro Dynamics (QED). That's a rather involved theory and probably well beyond the scope of this question. For the sake of a brief and sensible answer, let's settle for "because that's how the hideous mathematics works out".
You may also be confused by the notion of acceleration and also with how gravity works, which may seem different intuitively.
In gravity it is again the product of the two "charges" (which are the masses in this case) that result in the force (at least in Newton's gravitational theory).
But with gravity the acceleration is the force divided by the mass, and that means the acceleration of one body is proportional to the other body's mass.
We don't get that with charges because the mass and the charge can be unrelated and so the acceleration is not conveniently proportional to one charge.
My sense is that you're possibly intuitively mixing up forces and accelerations in this sense (probably not when you think it out logically, but intuition is not logic).