Us "nice" guys have a hard time saying no. Been there: Done that. Problem is though our "good guy" mark makes us easy prey for others. Where are they when WE need a hand? So, we have to learn boundaries, learn to say NO or LATER or else....
Having been self-employed for a long time, it's not nearly as easy as others think. They don't have a clue and many would just fail as they're not responsible enough to have to oversee it ALL. It was certainly a learning experience for me. And the taxes.....geesh. They'd freak having to pay their own every 3 months!
You're going to have to learn to tolerate their foot stomping, childish tirades, barging in on your already-set-schedule, say NO, NOT NOW, not feel guilty and not give in. After all, you have a responsibility to yourself, your schedule, your business, your income and your customers. They don't. They're clueless.
While families can be the worst, neighbors are right up there. I've started charging some for work...by the hour. They know it'll be fixed right...the first time.
So yeah, I used to have trouble with people like you describe, but not so much any more. More than a few I learned won't reciprocate when I need assistance. So that's my response the next time. After all, it works for them, eh? You quickly find out who are chronic users. Don't let them push you around, waste your time or get away playing this game over & over.
Build your healthy boundaries brick-by-brick. Start small, then work up. It'll get easier over time.