My family essentially uses me as tech support and I'm going to storm out of a family gathering because of this.
Do you know why your family uses you as tech support?
I'm the only one who knows about these things.
It's understandable that you are feeling burnt out as your family's technical support person. They need to call a professional and not unfairly depend on you, especially when you aren't being compensated. You should speak to them about this before it ruins your relationship.
It's too late now. I got tired of being the only person with computer knowledge.
I hope it's not too late, but it's understandable as to why you got sick and tired of your family taking advantage of your technical support knowledge. You're their family member, not their IT guy and your frustration is valid.