It may be that you just haven't found the right client. There are definitely clients who expect the moon and it's difficult when they are family. What I would say is work out a maintenance contract and stick to the contract. Set clear guidelines. I don't mind answering questions in a text from a client but if it starts to be an everyday thing, I would probably call attention to it. You deserve to get paid. If I get called in to consult (even for five minutes), I bill at a half hour minimum. This reduces the "oh I just wanted to ask you about..." and you achieve a healthier balance between work and life