Do I need the AEM HD water/methanol controller if my engine runs more than 35 psi of boost?

Not necessarily. The standard controller's internal MAP sensor is rated to 35 psi, but that doesn't limit the boost you can run; the settings only define when the pump starts and when it reaches 100% output. Example with a 1000 cc nozzle: Start = 5 psi, Full = 10 psi, then the pump starts at 5 psi, delivers ~500 cc at 7.5 psi and full flow from 10 psi up to 50 psi or more. The "Full" setting doesn't need to match your maximum boost. The HD controller (40 psi MAP) is only needed if you want injection to start and progress at higher pressures, e.g. on small engines running 2–2.5 bar where you want to start spraying later.