Because in reality, we're talking about a set of individuals, who, by circumstance, are related. They each have their own thoughts, beliefs and insecurities. And with that comes strong opinions.
I see my own family as fairly small: My mum, me and my kids. (My dad died years ago.) For me, they're the only ones that matter. But that doesn't mean that it doesn't hurt (even a little bit) when the extended family, the relatives that you hardly ever have contact with, talk crap about your life and your decisions.
These would be the same people that you'd probably never interact with at all if they weren't "family". The same people too, that don't have anything to do with your daily life and never care to take the time to understand what's actually going on. I know you know the ones that I'm talking about. The ones that would prefer to gossip and chat behind your back rather than have the backbone to say anything to your face. The ones that feel that the best thing to do in their lives are to judge others when they should be judging themselves and question their own choices, but they don't because that makes them feel bad as a person; Easier to lash out at someone else and bring them down.
But that doesn't mean that it doesn't hurt, even a tiny bit.
I know that they're judging from a place of their own hurt and pain, but that doesn't make it alright. No one has the right to make judgements on your chioces, especially when they have no idea of everything that's going on, and haven't bothered to stop and find out, usually because they fear that their judgements will be automatically dismissed. And then they'd have to stop playing their game of making others feel bad so they can feel better. And that's no fun.
Me? I'm going to let them play their games and have their "fun". It's not going to change or make me question my choices and my life. I know that I've acted in the best possible way. I've done what's right for me and my family that means the most to me.
And you should feel the same way when this happens.
Real family is who you make it to be. It doesn't have to be a relation through blood or marriage. It can be your closest friends or colleagues that have your back and are there for you when it really matters. Real family are the ones that support you and help lift you up; They don't bring you down or belittle you. Sure, they may help you question choices from time to time but they don't do it to change your mind for their best interests. Real family stand by you and the decisions you make. They love you unconditionally, even on your silly days. They're the ones that matter. Them and that person that looks back at you in the mirror every day.
Because if you're okay with who you see in that mirror, then nothing and no one else matters.