You might want to consult a couple more licensed real estate agents regarding the market value of your home. Most of the estimates should be in the same ballpark.
It could be that your friend is being more honest with you about the value of your home and the other agent gave you a higher number because he/ she already knew you expected it. This is called “Buying a Listing” (when somebody tells you they can sell your property for more than it is worth just to get your listing).
Or it could simply be that your friend is a good friend, but not that great of a real estate agent.
Mixing business and friendships is always risky to the friendship. On the other hand, if your friend is truly competent and was providing wise advice, she may be offended if you ignore the advice and choose another agent.