I can relate to so much of this! I've had a couple of relatively successful B2C products take off as side products in my time, and it is very hard not to develop a personal involvement in the support requests; whereas the detached, time-boxed, semi-automated approach is by far the best way to prevent it from taking over your life. Ultimately you're not a charity (unless you are) and, unless you specify an SLA, you owe these people almost nothing: I tend to suggest offering an automatic refund to anybody dissatisfied for this reason: then invest 95% of your time in whatever makes 95% of the profits.