Although it wasn’t as a founder, but I can relate, in one of a small startup I got hired as the first engineer, rest were a founder and sales guy and a part time HR girl, so as expected, I solely built the architecture, few fully fledged platforms, dozens of PoC, successfully delivered projects, then after 1.5y the second engineer got hired, now I’m guilty as probably you mentioned being emotionally attached to my work, after all, I really was invested in it, I even designed the icons for these platforms and the proper catchy names in addition to the software/hardware engineering design, to writing the docs and even pitching the work for technical clients since sales guy had no idea what the work was beyond the concept.

After a while, same thing started to happen, promises were made these platforms can deliver even though technically is impossible (so you can guess later when the client know these promises were BS), not getting invited to critical meetings, sales team (grew later than one guy) is gatekeeping the communication and only dripping to engineers the client requirements after they add their own unrealistic expectations, started to exclude me for training clients on how to use these platforms as only sales team are doing those (funny as most of the time, the first question they get asked and they are stuck, and ended up they calling me during the session remotely), and after long discussions that it isn’t possible to be carried by sales and need a technical team, they quickly hired a co-op to act as one during these sessions… among other issues, I call these situations are simply sabotaging the company/startup based primarily on greed, in this case it was by the sales and CEO followed later.

Now I had my lessons learned in that experience, but I’m sure your situation is worse being the founder, but I felt a good peace of mind after leaving them so hopefully you did the good thing.