It is sad – at first at least. You have been doing something for years, just to find out, that it is a boilerplate code. The conception was not the best, or You have reinvented the wheel. The outcome is simple – You have spent too much time on monetizing, instead of learning new, robust tech.
Don’t worry tho, on the other hand, it is a sign of progress. Sign, of going out of Your comfort zone, which actually is bad for You in the long run.
A friend of mine told me, that it is normal, and it will always be like that – devs should progress, but should not be overwhelmed by the feeling. Accept Your learning curve, admit that we make mistakes, but try to think about it in the future, to avoid stupid repetitions.
Have a good day, keep learning new things and enjoy opening Your favorite IDE 🙂