Dog ready?

Me and my boyfriend have been talking about getting a dog for a while, and my friends are 100% into it. We've done research. We want an adult, medium dog. We're going to adopt from a shelter s o the breed is probably going to be a mut. Everything is worked out, accept I went home to visit my family and as soon as I mentioned that were getting a dog it was all "it's to much of a responsibility" "Youll never get to go out on weekend again" and "you don't even understand" but I've wanted a dog for years and I understand the bad side. I know it will eat everything is love and I will at some point clean up it's pee, proudly a lot. I know that its hard to have a dog in a townhouse but I'm not looking at getting a huge dog. But now I'm second-guessing myself.