A quantum computer comprises a quantum processor and the associated control electronics used to manipulate the qubits at the core of a quantum processor. CMOS circuits placed close to the quantum bits and operating at cryogenic temperatures offer the best solution for the control of millions of qubits. The performance requirements of the electronics are very stringent and its design requires the simultaneous optimization of both the circuits and the quantum system. This paper presents the SPINE (SPIN Emulator) toolset for the co-design and co-optimization of electronic/quantum systems. It comprises a SPICE simulator enhanced with a Verilog-A model based on a Hamiltonian solver emulating the quantum behavior of single-electron spin qubits. A co-design methodology is proposed to derive on the one hand the specifications of the electrical signals to be applied to and captured from the qubits, and to ensure on the other hand, the compliance of the electronics in generating the required signals. This methodology results in an optimized qubit performance while considering practical trade-offs in the control circuits, such as power consumption, complexity and cost as proven by a practical design example.