Wow I am very happy for you.
Congratulations I was sure this was going to happen, what you did is too good to pass out inadvertly.
I did not think it was going to be so soon.
I am happy because in my mind Newton fulfilled its goal again.
Newton was created to give people like yourself the change to realize their idea without you having to be a physics source code pseudo expert. Of course not every body achieve that goal, but at least they have the opportunity.
I must said that now that you are supported financially the stakes are much higher people are looking at your work, you are going the get solicitation from individuals, commercial physics companies, your publisher, etc asking you to switch to a commercial engine.
In many case over 70% this is not because of quality more a marketing selling point.
Business and money changes everything, it puts lot of pressure on things that at first were simple, it also makes you loose control over what you really want to do.
Please do not hesitate to make that transition without any regrets, Newton is just a library.
We are very grateful already for what you’d done and I perfectly undertand these things.
Real business and life gets in the way and if you want so succeed you have to play along with the people with the money.
Like they said in the movies it is not personal it is business.