I'm too busy  to spend time with my girlfriend
What is the reason why you are so busy that you can't spend time with her?
My friends are more valuable than my time with her
I understand that friends are important but it is expected of you when you are in a relationship to make time for your partner. Otherwise, she may leave you
What if I'll tell her to get lost?
If you value your friend more than your current relationship. Then it's best for her to find someone new who respects her time.