Sounds like you are extremely valuable in the product you built.

In your experience it’s not just the manager direct report relationship that’s adversarial, it’s you against the whole company for the mismatched value they place in you.

You should use that as leverage. This comes with an mindset of looking out for yourself and not any loyalty to the company (I really wish that we could all find companies loyal and nice to their employees, in reality they are few and far between).

Something along the lines of “Hey I built our product. We’re making X in profit. I deserve Y in comp. I’ll give you a week to decide. If you reject I quit and build my own product or join another company.” Obviously add some fluff to reduce harshness.