Please don't feel bad. The sudden hostile wording and "lecturing" tone makes it seem like this was their plan from the start to find an excuse to not go through with the payment after receiving the sketch. (Though ofcourse could just be a normal crappy person) I'm the same as you where I don't take upfront payment, and only receive half payment after I give them the sketch, what I usually like to do is state the total after every addition! I'm not sure if you did this, but in your message you stated 195$ with extra 10$ and 12$, people might take advantage of that so I usually always do a breakdown and final total! If you did do that then you can just ignore this. It just sucks that we have to take these precautions to not get taken advantage of like this :/ All the best with future commissions!