I don't want to meet my girlfriend's family and go out to dinner with them
Why don't you want to meet your girlfriend's family and go out to dinner with them?
I am not really trying to spend time with them.
Meeting your partner's parents shows that you are interested in their life and that they are important to you. Learn more about your partner's parents and see if you can find things in common to talk about.
I know but I think it's a waste of time and I have my own family to take care of.
It is understandable that you may not want to meet your girlfriends parents as it can be an uncomfortable situation. Just know that it means a lot to your girlfriend to do this, and it is an important step in your guys relationship. It could offend your girlfriend and her family for you to deny going to meet them.