Tricky SF-86 self employment situation

My first employment as a software developer was doing commissions for a startup founder. It was informal and he failed to even issue me a 1099.

I was looking for more traditional employment after finishing my degree, but agreed to do a final commission to develop a mobile app if he paid me up front. It was going well until he invited me to be a "co-founder" of his startup.

When I refused, he had a total meltdown, screamed at me, and made horrible accusations and insults. I had no clue how to deal with the situation, so i just went no contact but kept working on the app since he already paid.

After a few weeks, he emailed me a big apology and blamed his outburst on a "dementia episode". I got positive feedback on a demo of the app, then gave him an APK before the deadline. All of a sudden he "hated it" but wouldn't elaborate and was demanding i make changes outside the scope. I just blocked him on everything at that point.

Now I have an offer that requires me to do the SF-86 for a TS/SCI w/ Polygraph. Is "self employment" appropriate since I paid my taxes that way and he had no control over my working conditions? Should I list him as the verifier? If I do list him and he lies or otherwise disparages me or tries to say I didn't work in the capacity I did, does it significantly complicate getting my clearance assuming I have relatively few/minor red flags otherwise?

Never tried to get a clearance before, I hope i'm just stressing over nothing but I just wanted to throw my situation out there to hopefully ensure that I list this in the best way possible to avoid any delays or issues.